Farm-to-table sourcing is downright tame compared with what some distillers and bartenders are doing to source spirited ingredients. They’re foraging for wild-grown plants in local parks, fields and forests.

“There are some weeds that you suddenly find value in when you can do something with them,” cocktail historian Jared Brown of Mixellany, told attendees at a Tales of the Cocktail seminar Friday on homemade cocktail components. Dandelion wine? Blecht, he ruled. But a homemade dandelion cordial was delightful.

More of the finds are less noticeable plants—yet, ones you probably pass by every day. To find them, CNBC tagged along on a foraging tour earlier this month that importer Frederick Wildman and Sons organized for local bartenders in Brooklyn’s Prospect Park. Barely off the sidewalk, forager“Wildman” Steve Brill, who has been leading NYC-area tours for more than 30 years, was already pointing out several varieties of edible plants—including several in the mustard family, and a relative to spinach—growing like weeds (which they are) along the path.

(What did we find—and make cocktail-worthy? Check out the video above.)

“If these things are working in Prospect Park, why couldn’t they work on 19th Street?” said Ann Marie Del Bello, beverage manager at ABC Cocina in New York City, who collected spicy Poor Man’s Pepper for possible planting in the restaurant group’s rooftop garden. The plant’s bite might work well with gin and Chartreuse in “herby” drinks, she said.

Foraging fits a number of broader cocktail trends. It gives bartenders an edge on unique ingredients, and a cool story to go along with them—especially if the ingredient in question has a role in folk remedies or herbal medicine.

“It’s interesting to find plants that other bartenders aren’t using or don’t know about,” Stilo Pimentel of Sweetwater Social in New York City, told CNBC on the tour.

It’s also a sustainable effort in farm-to-table venues. “There’s no reason you shouldn’t have farm-to-glass, too,” said Tim Master, a brand ambassador for Frederick Wildman and Sons.

Master, who is now in his second year of organizing bartender foraging tours for the brand, came up with the idea while visiting monks who make herbal liqueur Chartreuse. “[The father] started picking things in the garden, saying ‘This is in Chartreuse, and this,’” Master said. “I thought, why not show bartenders what they walk by every day on their way to work?”