Hay
Rabbits do best on timothy hay, but there are other types available. Alfalfa should be given less frequently to adult rabbits, because of the higher protein and sugar content. Other choices are orchard grass, wheat grass, broam, and oat grass. Remember regardless of the hay you chose, it should be readly available for the rabbits all the time. It is a good way for your rabbit to add fiber to his/her diet and ensure better health. Hay provides something healthy to quell your rabbit's urge to chew. Placing hay at one end of a litter box will encourage the use of the litter box. Remember, when choosing hay, make sure it looks and smells fresh. Do not choose a hay that looks brown or moldy or no longer smells like fresh cut grass. Always store hay in a dry place in a container that allows air flow to keep it from getting moldy.
Vegetables

A varied assortment of vegetables should be a part of your rabbit's daily diet. When choosing vegetables look for something fresh that is free from pesticides and chemicals.. Always wash your vegetables thoroughly before feeding them to your rabbit. When feeding a new vegetables, always start with a small amount so you can see how your rabbit reacts to it. Do not feed rabbits the leaves from houseplants as many are poisonous to rabbits. For a full list of poisonous plants, visit the Sacramento House Rabbit Society's page on the subject.
Your rabbit may enjoy some of the following vegetables:
Dandelion leaves
Romaine or dark leaf lettuce (no iceburg lettuce and no cabbage)
Carrot tops (carrots are high in calcium and should be given sparingly)
Broccoli leaves (stems or tops can make rabbits gassy)
Cilantro
Collard greens
Water cress
Kale
Mint
Parsley
Mustard greens
Dill
Bok choy
Pellets
Use a good quality pellet. What to look for is a pellet that is high in fiber and low in protean. Also you don't want a lot of sugars in it. A Timothy based pellet is ideal, if your pellets have Alfalfa in it you want to use very small amounts of it. What we look for for all our buns is a pellet this is made out of Timothy hay, that doesn't have any corn in it that's low on fillers and we don't want to see any sugars or mollases in it. Also, purchase fresh pellets, if your food is stale your bunnies will turn their noses up at it.
Water
Fresh water must always be available to your rabbit. Change your water with fresh water everyday. You can either use a sipper bottle or a dish, bunnies can drink out of both just fine. If your rabbit does not seem to be drinking enough water you can leave the vegetables fairly wet when you feed them.
Treats
Everybody loves a treat now and then, but to ensure your rabbits health they should be given only occasionally. Like human treats, bunny treats are often high in fat and sugar. Do not feed your rabbit items high in carbohydrates like breads, crackers, pasta, pretzels, cookies, chips, or cereal. Many commercially sold bunny treats are high in fat and sugar as well and should be given with caution if at all. Never give chocolate as it is toxic to rabbits.
Fruit is the best option for a treat, but again one must give it in small amounts because of the sugar content. We try to purchase organic fruits that we know are free of pesticides. Like vegetables, be sure that they are thoroughly washed.
Some fruits that rabbits enjoy include:
Blue Berries
Black Berries
Strawberries
Raspberries
Bananas
Pineapple
Apples (no seed)
Grapes (no seeds)
Raisins
Kiwi
Melons (no seeds)
Apricots (no pits)
Figs
Cherries (no pits)
And others
You can find a list of Rabbit Safe Fruits and veggies here: http://www.adoptarabbit.com/articles/packet/abcvegi.html