But the base of a bunny food pyramid actually isn’t filled by pellets. The most important ingredient to a healthy bunny’s diet is hay. Fresh hay should be provided to rabbits at all times so they can graze when they please. (See the real rabbit food pyramid in a PDF created by the San Diego House Rabbit Society.)

Hay for Rabbits: The Basis for a Healthy Diet

Picture a food pyramid for rabbits. What do you see at the base? If you chose bunny pellets, you wouldn’t be alone. Walking down the small animal aisle in pet stores usually reinforces the idea that bunny food takes the form of a brown pellet mix (and many times with corn kernels and other unhealthy additives thrown in).

Fiber for Digestion

Rabbits have digestive tracts that are specially adapted to break down fibrous vegetation. Hay provides the fiber necessary to keep their digestive systems healthy and motile. A disruption to a rabbit’s digestive cycle can cause gastrointestinal (GI) stasis, a condition in which the contents of the digestive tract become compact, and the rabbit has difficulty passing the mass through. Providing unlimited, fresh hay helps deter this serious, potentially deadly condition.

Roughage for Dental Health

Not only is hay necessary for good digestive health, it also wears down rabbits’ teeth, which continuously grow. Regular hay consumption helps prevent rabbits from developing sharp hooks on their teeth known as molar spurs. Molar spurs can be very painful, causing rabbits to stop eating. Once this happens, GI stasis can occur.

What Kind of Hay

For baby bunnies, alfalfa provides the high caloric content necessary for their development. Once rabbits reach seven months of age, gradually switch them over to timothy, orchard grass, and/or oat hay. For people with allergies, look for the second cutting of hay. When harvesting hay, the first cutting is a coarser hay that includes a lot of stems and seed heads (and inevitably, a lot of pollen). The second cutting consists of a softer hay that includes more leaves and fewer stems and seed heads, thereby reducing people’s allergic reactions significantly.

Where to Buy

You can usually find bags of hay at most pet stores. However, the absolute most economical place to purchase hay is direct from a local farm. Check Craigslist’s farm/garden section or your local classifieds to find a hay farmer. You can purchase hay in bulk (by the bale) for a fraction of the cost of a pet store bag of hay. One bale (stored in a cool, dry location) can feed a single rabbit for months.
If there are no farms in your area, don’t despair. You can also buy hay for rabbits in bulk online.

Nowadays, there are many reputable online retailers of hay, such as Small Pet Select. Use coupon code  
 MYHOUSERABBIT for free shipping on any size hay order from Small Pet Select. They offer a range of sizes all the way up to 60lbs.

From  http://myhouserabbit.com/rabbit-care/hay-for-rabbits-the-basis-for-a-healthy-diet/

Bunny Rabbit Hay Feeder

A wonderful way to provide fresh hay to your bun without having it strewn all over across the floor.  Made from 3/4 inch thick pieces of high grade all natural kiln dried untreated pin. We do not use stains or paint for bunny safety. These feeders are designed to last.  Easy open lid provides quick access for refilling, and two slanted 4 inch round feeder ports are rounded inside and out for smoothness. Comes with hand carved bunny motif on lid with routered edges to add a cute finishing touch.   Feeder has rubber feet for stability on slippery surfaces. 

Dimensions are 13" high by 12" wide by 8" deep for plenty of hay capacity and to fit all size bunnies. 

Hand made in northern Wisconsin by The Bunny Rabbit Toy Shop

$68.70 with free shipping within the continental USA

  80% of an adult rabbit's diet should be hay. Good quality hay is the most part of a rabbits diet and you're rabbits should Always have access to it. it helps keep their gut moving thus avoiding dangerous gut stasis which left untreated is nearly always fatal.  It also keeps their teeth nice and short and in good condition