But most of his talk focuses on the tastes of plants, roots, berries and herbs and on the various ways to saute, boil, steam or merely munch them raw. Those in short supply, such as yellow watercress, he doesn't pick. Others, such as sassafras, Juneberries and burdock, which Brill says are plentiful and easily regenerated, are yanked, snipped, picked and plucked as Brill meanders among the crowd.
Brill said his mother's death at 57, and his family's history of heart disease, prompted him to move away from junk food and meat and into a vegetarian lifestyle in the 1980s.
He eventually became a vegan and devotes part of his tour to urging foragers to try his cookbooks and check out his app. He met his wife when she came on a foraging tour Brill was conducting for a singles group in the late 1990s, and they have an 8-year-old daughter, who Brill said is growing up with a healthy, but not rigid, diet.
"I don't deprive her of birthday cakes when all the other kids are having it. But we try to keep the bad stuff on the low side," he said, defining "bad stuff" as refined carbohydrates, sugar, white flour, artificial chemicals and animal products.
Lest anyone accuse Brill of not appreciating the joy of old-fashioned comfort food, he notes that his recipes include one for chocolate truffles — thick, gooey sweets made from the beans of Kentucky coffee trees found in city parks — and a macaroni and cheese dish featuring whole grain pasta, black walnuts and grated tofu cheese.
For all Brill's claims to be bringing people closer to nature, Calvanese said his tours overlook one thing.
"Whatever you're eating in this park, remember, there's 38 million people coming through. And dogs. And everything else," he said. "I wouldn't recommend it."
Brill isn't worried. "This is how our ancestors lived," he said. "They knew what they were doing."