We examined sumac, whose berries can impart an appealing sour flavor. Late in the year, you can gather clusters of the berries, soak them in water at room temperature and you'll have your own wild pink lemonade.
Or use the same liquid as a concentrate to flavor salad dressings or sauces. Just be sure the berries are red. The poisonous variety of sumac has white berries.
We found chickweed and sheep sorrel growing free and unfettered, their culinary possibilities largely overlooked by visitors to the park.
And we had a vivid lesson in the importance of knowing what you're eating. As we passed through a wooded area, Brill gathered us around a white snakeroot plant in the underbrush. The attractive white blossom gave no hint that eating these leaves would be a bad idea.
"This plant has killed people who never even saw it," Brill said. Remember the story about young Abraham Lincoln losing his mother while he was still a boy? This plant was to blame.
According to Brill, a cow wandering through the woods apparently munched on the leaves of white snake root. The cow sloughed off the poison by discharging it through her milk. Mrs. Lincoln drank some of the tainted milk and succumbed to what was then known as milk sickness.
Once people figured out the connection - Brill says a Native American shaman helped point it out - cows were confined to pastures where their food could be regulated.
But it's hard to hem in foragers, and as long as they take the trouble to know what they're gathering, there's not much need to. There are plenty of foods all around us that are not only free, but also fun to find - and often more satisfying than grocery-store fare.
Baruch Yageel, 24, has been foraging for about five years. He's "usually" a vegetarian - in part because wild food seems to satisfy him more easily than cultivated plants. "When you eat foraged food, you don't crave that much meat," he says.
Susan Wagenheim, a physician from Albany, brought her 12-year-old son, Greg Weiss, to Central Park because he seems to have a natural affinity for plants. She would like for both of them to know more about the plants he finds so that they will know when they're safe to eat.
And what better way to build an affinity for wild plants than learning how they can offer a nutritious and tasty meal? That's part of Brill's talent.
Plenty of foragers can help you identify plants and tell you what to avoid. But not as many can do what Brill does - tempt you to find them so you can try a tantalizing recipe.
A wise observer once noted that a weed is simply a plant out of place. If you tend to relegate plants to the weed category unless you consider them either beautiful or useful, let a well-informed forager stretch your mind - and give your palate some pleasant surprises.