My buns LOVE the green carrot tops. They love dill, parsley of course and fennel topo. Fruit, both fresh and dried, needs to be limited because it is high in sugar and can cause diahrrea (carrots too!).....it should be limited to one small piece a week. Blueberries have excellent vitamins in them for buns. I wouldn't buy the bunny treats sold in pet stores...they are all alfalfa based.
Truth be told...buns don't REALLY need treats....it's just that we humans appreciate them, so we figure our furry friends do to.