I'm still investigating what the rabbits will eat.
Lemons. I threw some lemons into their pens just out of curiosity, though I didn't expect them to eat any. To my surprise every rabbit ate the rind off each lemon. But only a couple ate any of the pulp. So lemons are a winner, but just the rinds. The lemon trees I have here on the homestead have thick rinds and only a small amount of dry pulp. Not very good for juice, that's for sure. But their thick rinds are now an asset that I never had considered before. Finally a good use for these lemons!
Loquat leaves. The loquats aren't fruiting yet, but they are sending out new leaves. I've been putting two leaves into each pen and by the end of the day they're gone.
Blue snakeweed. I've got a lot of this stuff growing here that I'd like to get rid off. I've been pulling it out for years now. It seems that the rabbits like to eat a fistful of it every day. Great. Within a few months perhaps they will have eaten it all.
Pennywort. I don't have much of this growing here, but I gave it a try anyway. Rabbits munched it right down, stems included. Up till now I've been regularly hauling the excess growth out of the pond and throwing it into the compost. Now I'll feed it to the rabbits instead, turning it into much preferred rabbit manure. Seems that now I have a reason to start growing it in the other ponds too.
Kikuyu and molasses grass. I have to change my opinion about these grasses. When fed by themselves, the rabbits weren't thrilled by them. But when fed in a mix with lots of variety, they chowed these grasses down. I'm delighted to see that they find them acceptable because I have tons of the stuff growing around here.