My husband is, quite possibly, a genius

I realize that's a very grandiose statement. Even, possibly, a little self-aggrandizing. (He's all mine, ladies and gents!) But I don't think it's off the mark. Shane and I might disagree sometimes about core values and how to implement them (as in, I prefer organic and he doesn't care) but when it comes to thriftiness, I am very willing to admit that he's often the better half. Do I have examples? Better. I have a picture that clearly sums up my dear husband's "make-do" attitude.

Yes, that's part of an old wire hanger keeping the metal disc on the handle. See how resourceful he is? My creativity tends to be more abstract (writing, music) while his is the more concrete, how can I make this work type of creativity. So naturally, when our cheap pizza cutter broke a while ago, instead of spending the money to get a new one, he fixed it. And didn't tell me that he'd fixed it, so the next time I saw it I laughed. But it works! And we didn't have to buy a new one!
Until, that is, our mothers came for his graduation. Apparently scandalized at the idea that we'd have to use a less-than-perfect pizza cutting implement, they went out and bought us a new one without asking if we wanted one. It's very silly to me. Had they asked, I would have said that we were just fine with the mended one, and that I'd rather they save their money so that they could visit us more often! It's a delicate subject to bring up, though, and one that I've been pondering a lot lately.
I love Shane's mom, but she does have a tendency to send us...less than useful items. An old-lady-ish snowman sweater, clover earrings for St. Patrick's Day, and, well, this sort of thing:

Please note that they are for fun and safety.
How do I (gently and lovingly) inform my (new) mother-in-law that I don't really want this stuff?
These earrings will be going to Value Village on my next trip there.