I get dandelions at one of those superstores....Meijer Thrifty Acres, but I think they're located only in Michigan. But I can also get dandy's from one of the local produce stores....you just have to look for them or ask. I think dandy's are becoming real popular so hopefully stores in your area will start carrying them soon. And you can always ask the produce manager if he can get them in.
At the sanctuary we have found if we approach a health food store/organic produce store that they are more willing to donate their discards which we will give the buns as long as the produce is not nasty... These stores also tend to carry a lot more variety of veggies too. So you might see if there any such stores in your area and explain to the manager that you have bunnies and would like to give them the BEST produce and could he give you his discards or could you buy his discards at a reduced rate. For whatever reason chain grocery stores, like Kroger's, will NOT donate day old produce that they can't sell....I think they think if they start giving the stuff away, then everyone is going to want stuff for free..... So my advice is to ask your local stores if they'll make an arrangement with you regarding their day old produce first. Make sure they know you will be a regular customer or other things as well as the produce (mention your mom, other family members shop there). And remember too you are not restricted to romaine and green leaf lettuces....try the endive, or anything else that is dark....swiss chard, beet tops even! Our stores are starting to carry a lot of chinese cooking veggies...my guys love bok choy, napa cabbage, etc. The more variety you can give in a fresh veggie diet to the rabbits, the better...my vet says a variety of 5 diff greens/day but I just read I think in Rabbit USA that they advise 7 diff. veggies/day for buns on a no pellet, veg and hay only diet. Good luck! You're going to have really healthy bunnies!