Little green caterpillar

Can anyone tell me what these little guys are? They are a big fan of my cabbage plant. Which, so far, is the only plant they're eating. They're about an inch long. And they move pretty slowly. And they don't move like an inch worm, they stay flat. Any thoughts? I'm not too worried about the cabbage plant, so if they turn into some kind of pollinator then I'm all for them eating my cabbage plant.

This is in Atlanta GA