String, obviously.

And a magical ring, with an unlikely back history. Shiny. We all know how this goes. It is important to have something shiny in your pocket.

A really cool rock that you found while wandering about. Maybe also some twigs or an empty snail shell. Do not put the dead beetle in your pocket - yes, it is wondrously shiny but it isn't going to be friends with the cool rock. Yes, you really should have added a beetle pocket last time this happened.

Old tissue. A bit gross but usable in the kind of emergency that tissues help with. Like bad decisions around putting your face in a flower, or unexpected peeing.

At least three gloves. Never an even number of gloves. No. That would be weird.

The item of mystery. Did you mean to eat it? Were you intending to identify it later? Did it climb in all by itself? No one knows. It is important to make room for the mystery, and pockets are good in this capacity.

A broken thing. Because you were sad about it and thought that it might be lonely. Because you hoped to fix it, or use it in some way. Maybe you will. For now, it is a pocket denizen and you stroke it fondly and try to imagine what it's new life should be.

Bird seed. You had a bag at some point. Maybe you were feeding birds. Maybe you were spreading sunflower plants again. Enough seeds to play with, and maybe someone will come to your hand for a few grains.

The mortal remains of a bag, whose previous and heroic purpose has been forgotten. It may still prove useful.

Your hands - of course - are in your pockets some of the time, in skin conversations with everything else. Touching. Feeling. Remembering. Wondering if the little hard dry things are from last time you tried to take a dead beetle home with you.

(With thanks to Potia for the goblin prompt that led to this.)