Leda Meredith picks common mallow, which can be used as a cooked green or to thicken soups, in Brooklyn's Prospect Park. Kethevane Gorjestani

It's been almost 25 years since "Wildman" Steve Brill, the renowned New York City forager, was arrested for eating a dandelion in Central Park. Today, the local food craze and struggling economy have coincided to make foraging more popular -- and more acceptable to the authorities. Indeed, Brill is busier than ever with his edible plant tours of Central Park (he and the city made amends), and chefs at trendy restaurants across the country are incorporating foraged ingredients into their seasonal menus. Foraging groups in Los Angeles, Portland, and Seattle have created online maps showing cherry trees at municipal tennis courts and raspberry bushes in vacant lots. San Francisco (of course) has a Community Supported Foraging group, based on the agricultural co-op model.

So how hard is it to round up a fresh, free meal in an urban park that's really meant for pick-up soccer, dog-walking, and outdoor concerts? We asked expert forager and instructor Leda Meredith, author of The Locavore's Handbook and Botany, Ballet, and Dinner from Scratch, to show us how it's done one recent morning in Brooklyn's Prospect Park. Here's what she taught us. (See a photo gallery with some of what we picked.)

Lesson #1: Foraging in parks is legal...sort of.

"There's no law specifically against foraging in New York City," Meredith says. (Brill was arrested for conducting tours without a license, not foraging itself.) "Technically, there is a city ordinance against removing things from parks without permission, but that's really meant to stop people from, say, stealing rose bushes," she explains as we approach a patch of un-mowed weeds surrounding a sassafras tree near the park's main jogging and biking loop. Other cities tend to have similarly vague rules, and in her decade of foraging in New York parks, Meredith says she's never once been stopped. "If a park ranger did come up to you, you'd be in the clear as long as you ate everything on the spot."

Lesson #2: Avoid the "dog zone."

"Notice how I reached over," says Meredith, holding a stalk of goutweed, a celery-scented plant that can be used to flavor soups, that she retrieved from the middle of an overgrown patch.  Harvesting a foot or two inside the edges of growth should keep you clear of anything Fido left behind. You'll also want to avoid spots that have been sprayed with pesticides; most parks post warnings very clearly for the sake of children and pets, but it's worth calling your local park to find out for sure. Be sure to rinse your bounty well when you get home -- just as you would with any produce.

Lesson #3: Serious foraging yields more than just a few dandelion greens.

With just a little knowledge and effort, you can actually collect enough produce to significantly reduce your carbon footprint. In a good week, an expert like Meredith can forage enough wild edibles to meet half her veggie needs. "I filled two shopping bags in just a couple of hours here this weekend," says Meredith, who lives a few blocks away from Prospect Park. That means no fossil fuels were used to transport her meal. It's true that greens -- including dandelion, the foraging poster child, which is used in salads and can also be sautéed -- make up a pretty big percentage of the typical yield in the spring, but plenty of other choices abound, too. As in many urban green spaces, Prospect Park also has fruit and nut trees, berry bushes, and root vegetables. That's a comforting fact, says Meredith, considering that that if all of the regular food supply routes were cut off in an emergency, New York City's stores would run out of food in about two days. Of course, if a disaster struck in the middle of the winter, you'd be out of luck.

Lesson #4: It's a great hobby for cheapskate foodies.

As she stops to point out some lamb's quarters growing among the grass in the park lawn, Meredith recalls how she recently saw the same green at the famed Park Slope Food Co-op on sale for $5 per pound and labeled as "wild spinach." "I laughed because I knew the farmer must have gotten the idea after doing the weeding," she says. It's quite tasty, and she prefers it to cultivated spinach. It's not uncommon to find items growing wild in the park that are featured in trendy locavore restaurants and specialty markets. "Last fall I found 20 pounds of maitaki mushrooms growing here -- and as I was passing by the farmer's market on the way out, I saw some for sale for about $19 a pound."

Lesson #5: Speaking of mushrooms, always err on the side of caution.

Foraging dilettantes should zero in on just a few easy-to-recognize plants in the beginning, and even then, it's best to eat a small quantity the first time, says Meredith, as we come upon a patch of pokeweed. "For instance, these shoots are delicious when they're young, but they get toxic when they get older and start branching out." Meredith suggests taking a class to get started safely. The Yahoo! Group Forage Ahead is also an excellent place for beginners to get some expert advice; users can ask questions and even post photos. And The Eye Witness Guide to Mushrooms by mycologist Gary Lincoff is Meredith's pick for a mushroom-specific field guide.

Lesson #6: While you're at it, make sure to help yourself to some invasive species.

It so happens that many of the edible plants proliferating in parks are the very same ones that threaten to overwhelm local ecosystems. The goutweed and mugwort that Meredith likes to gather in Prospect Park were recently listed as numbers one and two on a 10 Most Wanted Invasive Plants list posted at the park's Audubon Center, and many others, such as burdock, are also considered highly invasive. "I once saw volunteers from a conservation group pulling it up -- and they were thrilled to hand it over," says Meredith, who promptly took the roots home and stir-fried them.

Lesson #7: Leave less rampant vegetation alone.

Of course not every wild edible is overly abundant-and you'll want to be judicious in harvesting those. (To find specifics in your area, check with a local conservation group, or look-up specific plants in the Center for Invasive Species and Ecosystem Health's online database.) "Make sure to leave plenty of flowers, so the plants will seed and proliferate, and never take the last of anything," Meredith says. This is for the sake of both the ecosystem and the bourgeoning foraging community. "On Sunday, I went to a patch of pokeweed I always harvest from, and I saw that about half of it had been neatly sliced away -- a sign that foraging is getting more popular -- and whoever it was left plenty for the rest of us," she says.

Lesson #8: If you want your food to taste good, don't trust old field guides.

"Those are edible, sure, but they're not very tasty," says Meredith as we pass some plantain leaves poking out of cracks along a concrete walking path. "But you see plantain leaves over and over again in some of these older books. You start to get the idea that the author never actually tried half of these plants." Chalk it up to the changing face of foraging. What used to be considered a survival skill for wilderness hikers is now the domain of sophisticated gourmets. The good news is, there are plenty of great resources that reflect the new zeitgeist. Meredith likes Brill's Foraging with the "Wildman," John Kallas's Wild Food Adventures, and Sam Thayer's Foragers Harvest. Her own two books and blog also have recipes and other foraging resources.

See even more of what Meredith found in Prospect Park in our photo gallery. And follow "Wildman" Steve Brill on a Central Park tour at Simple Steps.