My boyfriends mother kicked us both out and when we left she told me I am not aloud back in her house.. I have called her and asked when I can come get my stuff and she said she wants her son to pick it up and won't let me in to get my stuff now she said she is going to throw it away because he can't conme pic it up.. I just want to know can she do that?:

Depends, how long did you live in the house? You may have established legal residency requirements in many states. Even if you were there free of charge she might have to evict you. Not knowing all you details but I'm thinking she did an illegal eviction. If you bring this up to her she may rethink letting you get your belongings.