What do you do with your old baby stuff?

My baby is only 5 months old and my MIL asked what I'm going to do with the stuff he has already outgrown. I told her that I was going to put them down for when I have another (no time soon as he is my first) she said that it's crazy to save them that I should give them away. I wanted to have them to remember his little days but she said to look at his pictures 😞What did you guys do?