Berries, nuts, mushrooms and all sorts of edibles are growing wild in New York's parks. For the past few years, Steven Brill has been teaching people how to recognize them, how to gather them and use them for eating.

Mr. Brill is a resident of Briarwood, Queens, and he learned about wild edibles from his parents. “Then, at camp, the food was so terrible I ate berries all summer,” he said.

Alter graduating from college, the 34-year-old Mr. Brill said, he turned to nature for a living, charging $15 for adults (nothing for children, "what you can afford" for low-income persons) to accompany him on weekend park walks in the boroughs.

In Central Park yesterday, he found highbush cranberries, gingko nuts, berries from a viburnum tree, Mexican tea, sassafras, black haw berries, arrowroot, chicory, dandelions, mugwort, Japanese knotweed, ladies' thumb, wild violets, field garlic and beans from a Kentucky coffee tree—all edible.

“When something is sparse, you leave it alone,” he cautioned. “It's common sense to respect the park.” But Parks Department officials are irritated because “how do you draw the line between picking knotweed, and picking daffodils?” asked Adrienne Benepe, a department spokesman.

While it's illegal to remove plants, Mr. Benepe added that “unless it's a rare species, we don't enforce it.” Mr. Brill counters that most things he picks are weeds, or fruits and nuts lying on the ground.