A couple of things about barley rings:
If your rabbit is amenable, you can teach him or her to play "choose" in much the same way as you can a dog. Hold out your fists to your bunny, a barley ring curled gently in one hand, and once the rabbit knows you have a barley ring in your hand expect a bunny nose stuck into your hollow fist. Just don't expect your hand to be politely tapped as a dog would do.
Secondly, there are some egg-shaped plastic push-over-self-righting toys with a screw-off bottom and holes in. I don't know what they're called but you probably know the ones I mean. The holes only fractionally bigger than a barley ring.
Put a few barley rings in the toy and our DaVinci will pick it up and throw it all over the place to get the barley rings out. He'll also pick it up by one of the holes and run around the room if he thinks you might take it off him. It usually takes him a few minutes to dislodge all the barley rings in it. Every few seconds he sniffs the floor around the toy to see if anything has fallen out, but often Pineapple beats him to it and takes off with the catch. They know this game so well and recognise the rattle of the empty toy that as soon as they hear it they go mental.