Gifts

My mom likes to buy my kids big expensive gifts. She always goes away overboard, always outdoing my husband and I. I have told her they don't need any more toys as our playroom is full, but she doesn't listen. I told her I don't appreciate her out doing us and "santa", but she doesn't care. She says it's a grandma's right. What should I do? I hate that she always buys them more than my husband and I, and I hate that she doesn't respect my wishes. She does this for everything: Christmas, birthdays, Easter (she buys them a big basket, isn't that the Easter Bunny job?), Halloween (they don't need Halloween gifts, come on), Valentine's day, and just randomly throughout the year.