Pokeweed (Phytolacca americana) is edible when it is very young. I've eaten a lot of it. It is very poisonous once it gets any size to it. You can eat it up to about 6 inches - 9 inches if you are brave - and you have boil it through at least 2 changes of water to leech the toxins out.    At 9 inches, I recommend 3 changes of water.

I like it when it is very young, 3 to 4 inches high. After that, I think it tastes a bit acrid as a stand alone green, but still enjoy it in quiches.