Watercress: Watercress is a small, crisp member of the mustard family. It is slightly bitter with a hint of pepper. Its most commonly found in salads, on sandwiches and in soups. While watercress is available year-round, it peaks from April through June. Watercress mustard is commonly found in grocery markets in the gourmet mustard section. If you can’t find it, you can always make your own.