K&C Company Smash: they are easy-to-use scrapbooks with pretty pages (and they also sell lots of little things to go with them like stickers and date stamps). The idea is you can stick in anything you feel like, inhibition-free: you just "smash it in".
I think this situation also calls for copious supplies of pretty washi tape as well, however (a recent purchase from Washi Tapes was a birthday present to myself).
It's quick and easy and I think it will be a lovely keepsake book, full of happy memories and pretty little things. It's strangely liberating to feel that things I love holding on to now have a home, rather than gathering up in worrying little piles. I already feel a few degrees calmer!