What goes into the secret box?

Do you have a secret drawer, a chest or even just a tiny box where you hide
something with a special meaning to it?
I have a few, but it is very rare that i put something into them.
Maybe when we are done with the house repair, and i can move into my new studio, i will have a place for things like this. Then i can "organize" my precious treasures.
Like what? Well, for example an old really retro handkerchief my dad gave me. Very precious to me.
Or some painted stones i have been saving for years.

I would love to know what are YOU "hiding" in your treasure box?
Would you share it with me?

:-)