Collard greens have been cultivated around the world for thousands of years. My first encounter with them in India was during a trip to Kashmir; they were cooked long and slow in ghee and warm spices.

Mustard greens, chard, collard greens and kale are some of the most common you’ll see at grocery stores and farmers markets.

Often described as a cross between cabbage and kale in terms of flavor, collard greens taste “kind of bitter, but more earthy,” Tomlinson said. The rich green leaves also have a “leathery” texture ...