A basic rabbit pellet feed is essential...you can also offer hay,and pretty much any veggie or fruit..he'll let you know if he likes it or not,I can't think of anything really dangerous aside from wires!!!
good luck!

Thanks beeliz. Have you ever heard of putting chickens and rabbits together in a pen. I read on a web site where someone let their rabbit play with the chickens.

yup...I have my flemish giant running free with my hens. I have to feed her a special feed though,,,it has a microorganism in the feed to kill any coccidiosis it may pick up from the birds. it's a bacteria that can be dangerous to rabbits that is carried in birds feces. as long as the rabbit doesn't eat food that has been pooped on by a hen,it should be ok,,but I use extra caution with the special food...you can ask your feed store and explain the situation and they'll have it. the feed is a little more expensive,but it's worth it.
but the rabbit and the hens get along just fine! much nicer than a cage too!!

I have let the rabbit out for exercise a couple of times and they get along just fine. We have to put boards around the bottom of the girls pen so it can't get out. Thanks for the advice on t he food I will check in on it.