Is it okay to feed a rabbit just hay and vegetables/fruits?

I have a 4 month old rabbit and he eats just fine, but on the 22nd I adopted a 2 year old rabbit from my local animal shelter. There's nothing wrong with her, she just won't eat pellets. I've been feeding her celery and baby carrots (mostly celery and about two baby carrots a day) because that's the only veggies we have at the moment and we have no fruit right now. I've also been giving her grass from my yard (no pesticides!) and she likes that. She'll eat pretty much anything I give her besides pellets. I've tried hand feeding her, I've tried to force a pellet into her mouth, I've showed her the food bowl multiple times, but she won't eat them no matter what I do. She eats the hay as well. I know quite a lot about rabbits, but I've never heard of a rabbit that won't eat pellets therefore I have no information as to whether or not they can thrive on just hay, veggies and fruits.