OP your MIL bought new clothes, with the tags still on!? You are so lucky!!

My MIL buys used clothes and toys from the thrift store or good will (she drives a Mercedes and has a successful business, it's not like she couldn't afford new clothes) Most stuff is stained or broken - and we end up throwing most of it out. It drives me crazy. When DD was born, she sent a pretty big box of junk, every week for a few months. Every time she visits, she brings a car full of stuff. She has taken to hiding it in our house, putting toys in the basement, stashing clothes behind the rocking chair in DD room or the back of her closet. It's gotten a little bit better in the last year, but was really out of hand the last 4 years (after DD). Now with #2 on the way, I'm worried it will get crazy again. When DH told her about #2, he explicitly told her not to buy anything! FWIW, no amount of polite explaining, firm asking, or firm but polite refusing has worked. At least you can return, regift or consign what she gives you!