I lean over the grimy edge of the dumpster so I can sift through the jumble of garbage bags mired below with outstretched arms. Toes tipping to the ground,  the heavy metal lid of the bin pressing against the button on my baseball cap, I pluck a squishy, pendulous plastic bag from the mix and hoist it out of the bin.

I hold the straining, swollen bag at arm’s length, like a trophy fish.  It’s 20 pounds, easy, of freshly spent dark brown coffee grounds groaning against the thin white plastic film. I see no drippy leaks or cast-off paper cups or plastic lids, just a smattering of soggy paper filters. It’s a keeper. I set the bag, warm to the touch and ripe with the dank, roasty aroma of spent coffee beans from the tropics, on the floor mat of the backseat of the car and head for home.

I back away from the dumpster, rolling down the back windows and with a parting, sheepish glance into the rear-view mirror. I’m relieved to see no barrista running out the door asking me to explain myself.

But explain myself I will, for I’d do most anything for my compost pile. Even if that means getting, I see with a glance down to my lap, a smear of grease on the front of my good leather jacket, in return for some surreptitious dumpster diving for a morning’s worth of coffee grounds from the neighborhood coffee shop . Oh, well. It seemed a good idea at the time.

Coffee grounds already look like dirt but pack a bio punch. Not caffeine, but nitrogen. They make a prized addition to my pile.

It’s early November here in Westport, Connecticut, an affluent, artsy New York commuter suburb along the shore of the Long Island Sound. The trees that surround my small home on its flat, one-third acre corner lot have largely shed their leaves. Over the past few weeks I’ve raked colorful, crinkly leaves into piles and hauled them the blanket-full over to the log-walled compost pile I keep in the back corner of the yard.

The heap of leaves and such I gather is now head high and a broad-jump deep and wide. It’s the copious conclusion to a short but bountiful burst of green growth that culminates with the kaleidoscopic “leaf-peeping season” here in southern coastal New England. The autumnal leaves of hardwood trees in these parts are more than a tourist draw or seasonal scenic perk to living in Connecticut. I see each leaf as a bank slip of carbon and other nutrients and minerals, just waiting to be recycled into new gains over the coming year.

My pile is a final resting place for a season’s worth of green life given up for dead. But it’s more like a waystation, and all those dried-up leaves need a catalyst, a kick-start to their conversion into living new soil. Rich in nitrogen and other nutrients, the 20 pounds of recycled coffee grounds will deliver the same jolt to the heap of leaves and such I compost in my backyard as they gave to scores of caffeinated customers this morning. Sometimes it’s better to ask for forgiveness than permission.

Not only are coffee grounds sky-high in nitrogen, the granules have a microporous structure like charcoal and contain a wide range of useful microogranisms, reports Nicky Scott in “How to Make and Use Compost — the Ultimate Guide.” Besides being a rich source of nitrogen, which both kickstarts a heap of fall leaves and hangs around to supply plants with an essential element for growth, coffee grounds happen to look pretty much like finished compost — dark brown crumbly soil that acts pretty much like fertilizer once its spread around plants or cast wholesale across the lawn.

I’m acting locally, thinking globally, I tell myself, trying to rationalize my dumpster diving, lightening the coffee shop’s dumpster by a bag of trash and saving the garbage hauler from having to truck off that much more organic waste to some distant landfill.

All that coffee adds up — to some 500 billion cups a year, worldwide. In all, 7,658,780 tons of coffee are processed each year, making the brewed beverage the second-most valued commodity on the planet, behind only crude oil.

“That’s a whole lot of coffee — and a whole lot of spent grounds,” I read on www.mastercomposter.com, where founder Mary Tynes “focuses on innovative sustainability efforts worldwide, and encourages environmental mindfulness in personal choices and actions.”

“I teach composting because I believe it helps connect people to the Earth’s natural processes,” Tyne writes. “The more we learn about compost’s effect on soil, soil nutrients, soil structure, water, bacteria, fungi, insects and other creatures, it is obvious that Nature’s entire cycle of life was designed flawlessly.

“Environmental protection doesn’t just happen on the other side of the world.  Our first responsibility is to care for the patch of soil on which we live.  People who understand soil and how Nature replenishes it are able to make more responsible choices on both small- and large-scale environmental policies, and wider socio-economic issues.”

Which brings us back to coffee. Spent coffee grounds are the perfect compost input, Tyne says, because:

• They smell good.
• They absorb and hold moisture which is so critical to the compost pile.
• They are one of the few sources of nitrogen that is widely available year-round to people in urban and suburban areas.
• They are easily stored for days in a closed plastic bag.
• They are free.

Tyne surveyed followers of her blog and found that “more respondents have used coffee grounds for gardening or composting (87%) than actually drink coffee (81%).” She also found that “the idea of using coffee shops as a source of spent grounds had not occurred to most of the respondents in our survey.” Only 13% reported doing so. The chief reason being that most were too embarrassed to ask for other people’s garbage.

Tyne helpfully suggests “calling it ‘organic waste’ instead of ‘garbage’ — problem solved. Spent coffee grounds are a fruit nut that has been ground and had boiling hot water poured through it. It isn’t medical waste, or something that has been in someone’s mouth. It is the cleanest garbage around…You might be surprised at how fascinated some shop clerks can become with a person who finds spent coffee grounds useful.”

Some coffee shops around the country are making it easier to recycle and reduce waste; Starbucks has a “Grounds for Gardeners” program that offers spent coffee grounds to gardeners and composters, free for the taking in the bags originally used to ship espresso beans to the stores.

But this is a local java hut, and the last time I was inside I asked the girl behind the counter if she had any coffee grounds I could take home with me. She couldn’t quite process the out-of-the ordinary morning order, and it’s not easy to explain the concept of composting to a barrista when there’s three edgy people in line behind you.

“OK,” she relented. “There might be some in the bin, as long as you don’t make a mess…”

The mess is on me, at least for this day. But only the best for my pile, my insatiable, wondrous, mysterious pile.

My pile is my touchstone, a wellspring of life that nourishes me and my garden as I nourish it.

My pile is my balm. Some count bounding sheep to drift off to sleep; I turn over shovelfuls of compost in my head. After all, what’s a brain but an organic, chemical repository for gathered thoughts and things to be broken down and processed, to be composted. Visualizing, x-ray-style, what’s in my pile, sifting through its unseen layers and musing of its secret processes soothes my soul.

Garbage in, garbage out? That is only half-right about my pile, and that’s the beauty of it. The bits and pieces of digested life and matter that make up this heap of compost, in time and with some tending, always reconstitute themselves into something new and useful and whole, if only for a moment before being dispersed as fresh fodder and fertilizer for the future.

Each season brings a new and wholly unique pile, yet over the years each pile inevitably becomes one in the same. The longer and more deeply I dig into it, the more firmly my pile remains terra incognita, a Rubik’s cubic yard of shape-shifting organic matter that defies description.

Still, I try, if only for the exercise. My pile is a portal to the physical and psychic place where I spend my most agreeable waking hours, the backyard. On that front along, my pile is worth getting to know. I am comforted by the fact that there is a rich history of such landscape navel-gazing.

“To know fully even one field or one land is a lifetime’s experience,” writes Patrick Kavanagh, in Robert Macfarlane’s “Landmarks.” “In the world of poetic experience it is depth that counts, not width. A gap in a hedge, a smooth rock surfacing a narrow lane, a view of a woody meadow — these are as much as a man can fully experience.”

“While writing about landscape often begins in the aesthetic, it must always tend to the ethical,” writes Brian Lopez, also in “Landmarks,” a compendium of nature writing that aims to “re-engage a largely metropolitan populations with the marvelously specific and intricate habitats that continue to be smashed by industrialization, population growth and sprawl.” As a construct my pile may have modest value that extends beyond just one backyard.

“People exploit what they have merely concluded to be of value, but they defend what they love, and to defend what we love we need a particularizing language, for we love what we particularly know,” wrote Wendell Berry. I want to particularly know my pile, and to do that I aim to plunge into it deeply, to turn it over and again, to process it, and, in time, to reap in and share its rewards.

Karel Capek,  writing nearly a century ago in The Gardener’s Year, had it just about right in unearthing the essence of what draws me to my backyard garden, and keeps me there. It’s not the showy blossoms or ripening fruits, it’s something much more basic:

“While I was only a remote and distracted onlooker of the accomplished word of gardens, I considered gardeners to be beings of a peculiarly poetic and gentle mind, who cultivate perfumes of flowers listening to the birds singing. Now, when I look at the affair more closely, I find that a real gardener is not a man who cultivates flowers; he is a man who cultivates the soil. He is a creature who digs himself into the earth, and leaves the sight of what is on it to us gaping good-for-nothings. He lives buried in the ground. He builds his monument in a heap of compost.”

I could write a whole book about my pile.

So let me begin.

All the raw ingredients of fall start cooking quickly in my backyard compost pile.