What invasive plant is edible?

What is invasive? What is an invasive edible? Mint, kudzu, thyme, lemon balm. Can you name any more invasive plants? Why is that important? Think about it. Why do we work so hard to have food when there are invasive plants that are so easy to harvest, so easy to ignore and then harvest? Why do we want to work so hard when an invasive plant is there to supply our needs instead?