Whether used as a salad base, as a wrap, or simply to dress up a sandwich, lettuce is one versatile leafy green and a great source of fiber and antioxidants. The darker the leaf,... the more nutrients it has. Most lettuces are readily available year-round in most markets, but they are in season (and most delicious) in spring and fall. Read more here about the health benefits of lettuce and our tips for storing and cooking with it.