There are a bunch of good salad greens out there, and Garlic Mustard is very common and good. It is a biennial that grows low to the ground the first year, and tall with a small white flower the second. The leaves are edible both years, and have a mild flavor with just a hint of garlic. The stems are sometimes bitter, but you can remove them if it bothers you. You can harvest enough in just a few minutes for an ingredient to a wonderful wild salad. This is the second year Garlic Mustard growing among the Day lily at the edge of the cemetery near our house.
This is the first year Garlic Mustard in both the photos below.
As always, be careful there you harvest that no pesticides have been sprayed.