Another invasive species you can control with your appetite, Japanese knotwood looks a little bit like bamboo, but they're not related—even though it’s sometimes called “Japanese Bamboo." This weed might be harder to find if you don't live in the Northeast or Midwest, where invasive populations have taken root. But if you do see some, harvest the green and red shoots when the weeds are 6 to 8 inches tall, before they turn woody. Remove any tough leaves or rind and steam or simmer for a tart, rhubarb-like taste.
Photo: (cc) loopzilla/flickr