MIL Got Baby Clothes Out Of The Dumpster

So my MIL likes to dumpster dive. She gave me a bunch of baby clothes (18 weeks pregnant) that she got out of the dumpster and they smelled so bad. Like cat piss. I was polite and said thank you and have left them in my trunk. I was gonna trash them, but then got told by people that's rude, she went to the work to get them and that I should just wash them. Am I being rude by throwing them away. They are mostly toddler clothes so by the time she would be able to wear them my MIL will have most likely forgot.