Watercress
Piquant salad green and kitchen herb, hardy perennial to zone 4. An easy-to-grow perennial that needs little space. Super-nutritious, it has more vitamin C than an orange, more calcium than milk and more iron than spinach. According to University of Connecticut researchers, contains a compound that inhibits numerous types of cancers. .
If you have a swampy or poorly-drained place in your garden (or a leaky faucet) watercress can turn it to account in growing food. Otherwise, a container is an easy solution to saving water and keeping the watercress within bounds. In the wild, watercress often spreads over the top of slow-moving streams, rooting whenever it touches ground, like mint. I recommend growing in tubs or pots--it can be invasive in wetlands. We cannot ship it to CT or IL.