BELFAST, Maine — Last autumn, acorns were everywhere. A veritable torrent of the small, marble-sized nuts seemed to fall like raindrops from Maine’s oak trees, landing and rolling on the forest floor, walking paths, roads, driveways, even cars across the state.

The bumper crop of acorns — an event called a “mast year” by scientists — meant hikers had to watch their step and animals, including wild turkeys, deer, chipmunks, squirrels, crows and rabbits, had an all-you-can-eat buffet spread out in the woods. But the hungry wildlife weren’t the only ones who saw the acorns and thought “food.” Jim Merkel, a Belfast resident who is very interested in sustainability issues, did, too.

“I’ve had people give me some acorn flour as a present. We made pancakes with it, and it was delicious,” he said recently. “It’s really nutritious and very nutrient dense. And hardly anyone is processing acorns — just a few oddballs like me.”

Acorns have long been an important food resource for humans, though few eat them today. Paleolithic hunter-gatherer tribes around the world gathered and ate acorns, according to a 2014 article about sustainable acorn harvesting published in the Scientific American. Native Americans in locales as far-flung as California and Maine used them to make foodstuffs such as flour, oil and soup, and they also ate a lot of the nuts. According to the Scientific American, acorn nutshell is the “most abundant charred plant food residue in archaeological sites in all regions of central California.” There are a lot of reasons for its popularity, including the fact that it’s a good source of vitamin C, protein, fat, starch, magnesium, calcium and phosphorus. Acorn flour is gluten-free, has a high level of antioxidants and has a low glycemic index.

Sounds like the perfect food for today’s diets, right? But cooking with acorns is not easy, Merkel said. In raw form, the nuts are just about inedible because they have very high levels of tannins, which make them taste bitter and astringent. Before they can become flour for tasty pancakes, the gallons of acorns he gathered last September and October with the help of his 7-year-old son, Walden Merkel Cutting, and partner, Susan Cutting, must endure significant processing to remove the tannins and render them edible — and tasty.

First, Merkel said, it was critical they gathered the right acorns. A tiny hole in the shell meant a worm already feasted on the nut, so those were discarded outright — as were any that looked moldy. Then they were spread out on wire mesh drying racks that were placed in sunny windows and left all winter. Then, a few weeks ago, they began processing the nuts with the help of Belfast-based herbalist Steve Byers and his family. They cracked the acorns to get out the meat, then worked to remove the testa, the papery red-brown coat rich in tannins that surrounds the meats — similar to the coat around a peanut.

Merkel, Walden, Byers and his two daughters, 7-year-old Leah and 4-year-old Liza, and Molly Katz-Christy, a friend from Boston, plunged the acorn meats into buckets of water last week and enthusiastically agitated them to remove the skins.

“This, to me, is really fun,” Merkel said. “I really enjoy wildcrafting.”

After most of the skins were taken off, the next step was to grind the acorn meats into flour, which they did with the help of a hand-operated grain mill and an electric food processor. Once that step was accomplished, it looked like coarse flour, but it was far from being ready to use. Tannins are in the acorn meat, too. One way to remove it is to leach it out by immersing the flour in 5-gallon buckets of water, which would need to be emptied and refilled with fresh water periodically. This part of the process should take five to 10 days. After that, once dried, the flour will be ready to use. The tannins also can be leached out faster via a hot-water method, but that way is more energy-intensive and Merkel and the rest of the group opted against using it.

“It’s so good. It’s so nutty,” Byers said of the finished product.

Katz-Christy, who has processed acorn flour before, agreed. “It’s the best flour you’ve ever had,” she said.

Because Merkel and Walden gathered so many acorns last fall, they expect to wind up with 20 to 30 pounds of acorn flour. Experts recommend storing acorn flour in the refrigerator or freezer because it is high in fat and could spoil. Some of the Belfast group’s finished acorn flour is likely to be consumed quickly, in the form of pancakes served with homemade maple syrup. Historically, Native Americans in Maine and elsewhere combined processed acorns with bear fat and dried blueberries to make pemmican, a nutrient-dense and easily portable food.

“Just a few pounds could take you for several days,” Byers said.

Even though making acorn flour is a fairly labor-intensive process, it’s worthwhile, they said.

“I love everything that has to do with wild edibles and eating off the land,” Merkel said. “It feels like it’s timeless, like something that would have happened 10,000 years ago.”