That's great! Your Grelos is what I know as Wild Field Mustard, Brassica rapa. It's not native here in North America, but now is a widespread weed. It's amazing, but true -- this species was bred into Turnips, Rapini, and Napa Cabbage! So many different forms of the same species, just by maintaining the genetic selection. I forage a lot of wild field mustard. I tell people that finding one plant is like finding a $20 bill. There is so much of it that is good to cook with. It's wonderful!