Stinging nettles
From Burden's Landing
Foraging and Planting Nettles
They grow like weeds, because they are weeds! Be careful of where you plant them. A separate pot is best.
Plant and harvest in early spring before they flower. Don't eat them when they're tough. Not only are they not tasty, they have compounds that may not be good for your kidneys.
Cut at node, just like you're pruning them. You'll be able to harvest them multiple times.