Lamb's lettuce
From Cookipedia
Corn salad (Valerianella locusta (Linnaeus) is a small dicot annual plant of the family Valerianaceae. It is also called Lewiston cornsalad, lamb's lettuce, fetticus, field salad, mâche, feldsalat, nut lettuce and rapunzel.
Habitat
Corn salad grows wild in parts of Europe, northern Africa and western Asia. In Europe and Asia it is a common weed in cultivated land and waste spaces. In North America it has escaped cultivation and become naturalized on both the eastern and western seaboards.
Like other formerly foraged greens, corn salad has many nutrients, including three times as much vitamin C as lettuce, beta-carotene, B6, B9, vitamin E, and omega-3 fatty acids. It is best if gathered before flowers appear.