I could hang them outside, but I'm always afraid a bird is going to poop on stuff like that.

Actually I don't know WHAT the material is. I asked my mom if they were wool, and she said no, but didn't know what they were. They have a lining in them, and they were gotten at JC Penny because they have a label in them with the Penny name, but the only other tag in them is the one that says 'DRY CLEAN ONLY'. There's no tag anywhere that says what the material is. I'll probably end up taking them into my dry cleaner just to ask them what the material is.