Priceless.
I'm going through my mother's things right now (she's in a nursing home) - and she collected those things too!
I get bogged down on cleaning when I run across a drawer full of my old report cards, Mother's Day cards I made for her out of construction paper with crepe paper flowers & glitter, crayon drawings of my house and my dog, and pictures of us playing board games. I laugh and cry at the same time.
You are right - they are priceless.
:-)