I kept many mementos from when my kids were little. Drawings, report cards, their first lunch boxes, favorite books, clothes that had significance (first pair of overalls, shoes etc.) They were kept in my keepsake boxes, the kids all knew about the boxes, and as they got older, they'd bring me stuff to put in their keepsake box. As the kids left home to make lives of their own, I'd give them their keepsake boxes. There were half a dozen or more for each child. I told them flat out that as far as I was concerned, they were theirs to do with as they wished. They could take them straight to a dumpster if that's what they wanted.
Interestingly each of my five kids went through the stuff, laughing at some of the stuff that was important to them when they told me to keep it. They all LOVED that I'd saved their favorite books. The ones who have kids have passed those books on and I get such a kick out of seeing a grandchild read or be read to from one of the books that belonged to their parents when the parents were little.
I also get a HUGE kick out of seeing some of the clothes that my kids wore being worn by their children!!! It's still happening and I LOVE it.
Over time, over the years, I've slowly pared down my own belongings, offering things to the kids, getting rid of what they don't want. I have very little of significance left, and that's just the way I want it. I'll keep the stuff with me till I die, bequeath certain things to certain people in my will, and the rest can be tossed. I've already discussed with my kids who wants what after I'm gone, to keep the bickering to a minimum