If you grow grass inside. Can you give it to your bunny to eat?

You can certainly grow "cat grass" and feed it to your bunnies.  You can get the seeds at plant stores, and they are usually either barley, wheat or some other cereal grain.  Just drop them in some potting soil, wait a couple of weeks and let the buns have fun eating the sprouted plants.

If you are referring to regular grass seed, I would be concerned about pesticides and preservatives used in packaging the seed.  Since lawn grass seed is not intended for consumption, who knows what they put into it.

My bunnies are very fond of wheatgrass, which you can grow indoors.