Sorrel is a name for a group of leafy greens you can often find at farmers’ markets in the spring and summer. It goes well in salads, stir-fries, soups, casseroles, marinades, and with cream, yogurt, cheese, and fish.
Dock, another name for garden sorrel, is fresh, leafy green. Most grocery stores have a produce section where you can find garden sorrel and many other sorrels. It can be cooked or made into tea, juice, or jellies.