Memeory box ideas EDIT

My son was still born at 22-23 weeks in September. I have a memory box (I got from the hospital) with little bits and bobs of his things in (blankie, booties, candle, footprints ect)

Was just wondering what everyone else has in their memory boxes that they can keep adding too? I'm thinking of putting a birthstone of his actual birthday and his due date in.

I want to add some more things that I can look at to remember him but I just don't know what

I kind of want to put something in that I can add to every year, kind of like a tradition thing so I know I can do something for his birthday. I just don't know what

EDIT: sorry m don't think I made myself clear.... I already have everything I have of him in there (tests, his blanket and booties, ultrasounds, hospital wristbands, foot and hand prints ect) I'm looking for something j can add to each year