Good question from Sarita. Also, you can always order a supply of food online, and I (am not paid to, btw) can highly recommend the binkybunny,com store. I have always used Oxbow Bunny Basics-T for adult bunnies for pellets. It is much less expensive to order than the mark up in the big box pet stores. What you can do is order a bigger bag to have it last a couple of months or more, get mini-bale hay and some treats and toys, then the shipping cost makes it worth while because you won't have to order again for several months.
Also, if you have a local vet some of them sell rabbit food. You can ask your vet to order in Oxbow pellets to sell to you regularly, which may make it worth her while.
Any pellets from the tractor store need to be plain with no additives (like yogurt drops). If you get the names, you can find their website and look up Oxbow's pellets and compare lists of nutrition content. You want lowest fat content in the ones you buy.