I don't usually buy things specifically for chickens, so they only get the unwanted bits. But you can get a lot of bang for your buck that way. The leaves and stems of cauliflower, rinds and seeds from squashes and melons, carrot tops with a bit of the root. I tossed a carrot top from a carrot as long as my forearm and it took the flock 3 days to make it disappear.