Is it okay if I tell my mom to stop gifting me junk?
I wonder why you feel this way, most people would love any gift they get. I think you are joking with me. Does she really send you a lot of junky gifts?
Yes, I'm sick of getting useless gifts all the time.
You should continue to tell her no, and immediately donate or toss anything she brings. Avoid losing your temper and remember that she is just trying to be nice.
I'm going to talk to her and continue to say no.
A gift is all about the thought behind it, be nicer to your mom and just explain you don't need those things she gives you and it's only to save her money. That way she will think you are caring about the money and not the gift itself. Otherwise just take the gift and say nothing, because it is a grateful thing to do.