Yes. Though you must be sure not to feel them grass using the clipping from a lawnmower, as this can ferment and cause gastrointestinal problems. Instead, you should allow your rabbit to naturally graze in the garden as it would do in the wild. Furthermore, don't even try to switch your rabbit from hay to fresh grass overnight as this also can cause digestion issues. Instead give them limited time in the natural grass during which they can graze to their heart's content, then for the remainder of the time provide them with hay.