The modern farm-to-table movement has renewed interest in heirloom fruits and vegetables. But long before the trend, John Coykendall has been on a mission to preserve rare heirloom seeds and document their heritage."We lost so much over time. That's why it's so important now to save what's left," says Coykendall, the master gardener at the luxurious mountain retreat Blackberry Farm in his native Tennessee.Coykendall has more than 500 varieties gathered from small farmers and backyard gardeners around the world. The bulk of his collection comes from the American South — Appalachia and here in rural Washington Parish, La., near the Mississippi state line."It's the unique sense of place that you find here," he says. "They've retained their sense of integrity, character, way of life, farming ways."On a recent visit, he stopped by the Circle T Feed and Seed in Franklinton, La."For me it's especially the seed," he says, walking straight to the back of the store to an aisle of cardboard bins filled with vegetable seeds.Dressed in denim overalls, Coykendall rummages through the seed sacks looking for varieties you can only find here — like the Louisiana purple pod bean."It makes a pretty bean — beautiful display growing," he says. "The pods are solid purple but when you cook these, once the steam hits them, they turn green again."Coykendall is like a walking, talking seed catalogue. For nearly half a century, he's been collecting seeds and the stories of the people who grow them.Coykendall keeps detailed journals of all of his seed expeditions, something he calls "memory banking.""A little bit of ancestral history," he explains. "Where you were living? Where did this seed come from? Did it come from your grandmother or grandfather? Was it brought here from somewhere else? How do you grow it? How was it cooked?"He's a trained artist as well as a seed preservationist, so the journal entries include lovely drawings of the seeds, their plants and the surrounding landscape."They're little artifacts, each one of them," says Louisiana producer Christina Melton. She's helping Coykendall organize his journals into a book. There are more than a hundred of them."It's something that that is a real resource for people in trying to re-establish people's ties to the food that they eat," she says.Melton made a public television documentary about Coykendall called Deeply Rooted. It's been circulating for private screenings at Slow Food USA chapters around the country. (You can view the full film here for free through Nov. 25.)On this trip to Washington parish, the subject is peas as Coykendall visits local farmer Mike Lang."Like we say, John, we ain't never met a pea we didn't like," Lang says.Lang lives, and plants, on what used to be his grandfather's land, named Graybuck Holler.Sitting around a table in the sun porch, the men sift through Lang's collection of field peas, many of them varieties that Coykendall has found and restored to the community."We're saving it now," Lang says, showing the seeds he keeps stored in plastic bins in his freezer."It's in our court now, Coykendall says. "Something happens to it — now it's our fault."One pea they are saving for posterity is the "Unknown Pea of Washington Parish" — a prized variety that had been passed down for generations, but then went missing from local farms for decades."The Unknown Pea goes way back in time," says Coykendall. "Probably late 1800s, early 1900s. And they called it the Unknown Pea because nobody knew where it came from."Coykendall says farmers used to plant the Unknown Pea right in their cornfields — the stalks serving as stakes for the climbing pea shoots.Without even looking at his notes, he can tell you this kind of history about hundreds of seeds."It's kinda like having grandchildren," he says. "You've got to remember their names.""And their birthdays," adds Lang.The birthdays are when certain varieties gained popularity on U.S. farms. But Coykendall says most of the plants have deeper roots."The genetic homeland of the field pea is the Niger river basin in Africa." Says Coykendall. "So they came over in association with the slave trade."Knowing the history of our food, he says, is part of knowing who we are."And if somebody doesn't record it, put it down, it's going to be lost for all time," he warns. "That goes for the seeds. This is the living part of it. Living heritage. Our agricultural heritage."Coykendall says the work has grown even more important as industrial farming practices threaten the old farming ways, and the bio-diversity of crops.Some of his collection is available to growers through the Seed Savers Exchange — a non-profit group that preserves heirloom crops, and stores endangered seeds in an underground freezer vault in Iowa. Copyright 2017 NPR. To see more, visit http://www.npr.org/.