Even though it bothers you, don"t let her see you upset. The purpose of her gift is to see that it got a reaction out oF you. Politely and mechanicaLly say thank you. After a while of seeing non+reaction, she will either quit or (shudder) raise the rudeness factor. Remember, you can"t change/control others, but you can change/control your reaction. Give unwanted gifts to the peopke of your chiuce (mailman, women"s shelter, teacher, etc.). Don"t let it make you into the ugly soul she has.
Okay. You can have some fun. Buy her cheap and "pintless" gidts, like a child"s book (like Cinderella or Snow White because she acts so childish and like the wicked stepmother), or hemorrhoid cream (because see has something bothering her and oh my what a kind and observant daughter-in-law you are), or a box of chocolate (because she loves it so much and you can't figure what else she woulD like). Or just a card, because evenn though that's not is done in Germany, it is after all, the "thought that matters".