If you’ve been to the South, you know benne.

It’s where seed activist and Husk chef Sean Brock uses benne seeds to make savory wafers smeared with pistachio hummus. And chef Benjamin B.J. Dennis, an unofficial spokesperson for Gullah Geechee cooking—the seafood- and plant-based cuisine developed by descendants of African slaves living in the South Carolina and Georgia Lowcountry—uses the seeds to thicken soups and stews, as his elders did.

At first, the benne plant was grown in slaves’ gardens.

The benne seed is derived from the same plant as modern-day sesame seeds, Sesamum indicum. Like many heirloom ingredients from the South, benne has a fraught history. “Benne” is the word African slaves used for the seeds, which were brought on slave ships from West Africa—along with many other crops, including red peas and Carolina Gold rice—to the U.S. in the early 1700s. At first, the benne plant was grown in slaves’ gardens. It was used to thicken stews and sauces and add fat and protein, along with a rich and nutty flavor, to food. The seeds were especially important when meat was scarce in their meager diets.

Benne seeds have been saved from extinction, and heirloom varieties are now available through Anson Mills.

The seeds were eventually adopted by plantation owners, given benne’s ability to improve soil quality, and rotated as a crop with rice.

When farmers realized the seeds could be commercially grown to produce cooking oil (at least before the cottonseed oil boom, which superseded the fervor for benne seed oil), they started prizing high yields over flavor. By the 20th century, that shift led to the milder-tasting seeds that are grown commercially today as sesame seeds. (These sesame seeds are now also used to make Charleston’s famous “benne seed wafers,” sold at the city’s lively cruise ship terminal.)

Heirloom benne was nearly extinct in the U.S. until Glenn Roberts, who is famous for reviving antebellum varieties of grains and beans, started growing and selling benne seeds through his company, Anson Mills.

Raw heirloom benne seeds are brown and look like toasted white sesame seeds. Their flavor, however, is much more pronounced and slightly more bitter than common sesame—especially when toasted. In her new book, Poole’s: Recipes From a Modern Diner (Ten Speed Press), North Carolina chef Ashley Christensen observes that they have a “coffee-like depth”—one reason that, instead of being used as an afterthought garnish, they stand out even when sprinkled over spicy, umami-rich foods. They also give sweets incredible complexity, like a dark caramel.

For example, Christensen stirs the seeds into crunchy toffee that she blends into a rich benne ice cream. “Think Ben & Jerry’s [Coffee Toffee] Bar Crunch on steroids,” she writes about one of her favorite Southern ingredients.

If you’re curious to taste benne seeds for yourself, you can buy the seeds as well as benne cake flour—the by-product left after the seeds are pressed for oil—through Anson Mills.