Mushrooms
Mushrooms will appear at the barn levels. Normally they are white, but they can be included in any bunny's path. This will then make the mushroom's color match that of the bunny. Do not use too many of them with one bunny because you must clear all of them out to earn a three star rank. If you use too many for one bunny, another bunny might not be able to eat all their crops.
Preserving lives
If you do not leave a level once you start it or commit to a route that does not get you all the crops, you will not have to worry about using a life. If you set up path that ends badly, tap back to reset the route. Be careful; if connect the path to the rabbit hole, the rabbit you are controlling will automatically begin walking down the path. Do not commit to a path until you have planned it out to get all the crops. There is no time limit, so plan carefully.