“There are two kinds of people who come to events like Earth Day,” Jane Richlovsky was saying, “paper people and signature people.”

Both kinds of visitors were keeping busy among the rickety card tables, as 20 or so environmental groups displayed their wares on the lawn before the Chicago Academy of Sciences on a Saturday a couple of weeks ago. Paper people collected literature on alternative energy sources, recycling, preserving Puerto Rican rain forests, and stopping animal experimentation, while signature people signed petitions supporting these and other diverse causes.

Richlovsky was sitting at the Citizens for a Better Environment table, which was set up between the water and energy sections. It was one of the few displays that offered no petition, but the free literature was popular: “Radium in Our Drinking Water,” “Common Household Hazardous Wastes.”

She could have mentioned a third kind, the argumentative people. I was talking with one, an elderly man with stern eyes and a beret, while waiting for the edible-plants walk to start. He asked me if it was true that someone was going to lead a group around Lincoln Park and show how to forage for food.

“But it’s against the law to pick food in a park,” he said. “You know how the Park District squawks when you break just a little branch!”

After a time the waiting grew tiresome for him, and he wandered off in search of fresh arguing partners. About eight other people showed up before Wes Wagar, our host, led us off. He is a short man of indeterminate age who regularly searches for edible plants with a group called Foraging Friends. He spoke softly and at the ground, so that we had to crowd around closely to hear what he was saying.

“What are we looking for?” asked a short, pudgy woman who had been sitting at one of the energy tables.

“Plants and mushrooms,” said Wagar, looking at the ground. He led us around the comer of the Academy of Sciences building to a shady plot.

“This is burdock just starting to come up,” he said, pointing to a squat, nondescript plant with broad leaves. “The Japanese eat a lot of it. They dig up the roots. You can also dig up the roots and use them as greens.

“It’s highly recommended by herbalists.”

“I wonder if it’ll help my bursitis,” said the energy woman.

Nearby, small mushrooms sprouted from the loam. Wagar showed us how to conduct a spore test, which is used to distinguish edible mushrooms from poisonous ones.

“I think I’ll stick to buying mushrooms in the store,” said an unconvinced forager. It would take Wagar a little longer to make converts of his audience.

Eyes constantly roving, he moved to a patch of lawn a little further on. He pointed at a dandelion, which I recognized from my lawn-mowing days, and said that every part of the plant was edible. And as an herbal remedy, dandelion leaves, when rubbed on a cut, were “better than a Band-Aid.”

The energy woman was enthusiastic. “You can make delicious dandelion wine,” she said.

Near the entrance to Lincoln Park Zoo, Wagar stopped before a wide bank of well-trimmed bushes. Saturday afternoon crowds flowed by. “This is honeysuckle,” he said, “which is not edible. But there’s no reason why this couldn’t have been planted with something edible. Same with the trees–they could be apple trees. That’s one of our beefs.”

A few steps on, just outside the zoo’s chain-link fence, Wagar pointed to more low weeds that I would have passed without a second thought. As the group gathered around, he explained that these thistles were tasty when boiled.

Inside the fence, a female zoo employee, her interest piqued, came over to see what we were looking at.

“Oh, I’ve never eaten thistles, but there’s a lot of burdock up here,” she said, pointing to a low rise beyond the fence. “I have that all the time. It’s great in stir-fries.

“I always come over to see what tours are doing. They’re very educational.”

Our group wound its way through the park, trying to assimilate and remember what to do with plantain, shepherd’s purse, waterleaf, and yew berries.

Japanese knotweed was easier. Foragers in the know find it “in waste areas all over the city, according to Wagar. Harvested when about 12 inches high, the stalks can be cooked just like asparagus, though they have “a real lemony flavor.”

But it was the wild onions that really convinced the remaining skeptics in the crowd. Not only were they pungent and delicious, but it seemed appropriate to munch on them in the city that had been named after wild onions. A ballpark frank, I thought, would taste sensational with a handful of these.

We took the tunnel under Stockton Drive and crisscrossed the lawn in search of more herbs. I had a terrible feeling that I might stomp on some delicacy just as Wagar was getting ready to point it out, so I stuck to the back of the herd.

At a broad flower bed we stopped to sample some mustard leaves (which would have been the finishing touch on that hot dog). “That’s got a real nice flavor,” said the energy woman, chewing thoughtfully. Nearby sunbathers looked askance.

Nearing the end of the field trip, Wagar stopped to try a hawthorn berry. “Pretty dried out,” he said, noting that the berries dated from last fall. “The best time to pick ’em is just after the first hard frost.”

“We used to throw ’em at each other when I was a kid, but we never ate them,” said a man in a bright green shirt who looked as if he might have felt at home on a golf course on this sunny afternoon.

Back at the starting point, Wagar invited us all to a Foraging Friends outing. He claimed that he could find food in Chicago’s parks and forest preserves throughout the year.

Before the Earth Day stage, about a dozen people were participating in some sort of religious ritual. They marched slowly in a circle, while a young woman swung a censer that reminded me of Catholic churches. Across the circle of card tables, it looked like Jane Richlovsky was fending off an arguer. I headed for the White Hen across the street, thinking that it was time for some beer and a sandwich. I would be sure to get it on whole wheat.