Wheatgrass in the back left, got it at the grocery store. He doesn't eat it that I have been able to tell. It's gotten really ratty but it works for me. Could easily put it in a pot or start from seeds. Would be easy to keep a fresh pot.
Clover in front left. I got this from my garden, I'd bought seeds and planted them a few years ago. I'm not sure if it would grow well in a pot, it's only been in a week or so. We've started seeds and they are doing well.
Middle is collard greens. I don't think they are getting enough light, but I didn't think they would last so long as they have.
Right is collards and turnip green sprouts. We have been starting these in trays under a grow light. I know other folks who grow greens and lettuce mix right in the cage. They sprout quick, you wouldn't need too deep of a pot and they wouldn't need as much as water as a bigger plant.
Back right is fake grass