This is Green Ice lettuce, a looseleaf semi-heading type. This patch here is from seed that I saved. It is the best tasting and sweetest of the lettuce varieties that we have grown here. It is enjoyable to eat straight, as is, out of the garden. To save seed, leave several plants in the ground and they will shoot up a flower stalk. It will grow 3-4 ' tall and will have hundreds of tiny flowers. When the flowers finish blooming, each flower head will have several seeds in it. Cut the whole stalk and let it dry and save all the flower heads. It will look like a mess of debris, but scatter it on tilled ground for a fall crop of lettuce. That is how I got the patch that you see in the picture.