For me, its my Unk's hammer.
Leading in from a comment I made on another thread, my Unk was my great-uncle, I couldn't say it when I was wee so he was my Unk.
He died in 1987 and I miss him every single day.
And that fecking bastard up the road has the fecking hammer that my Unk gave to me when I was a wee girl and that we used to make wooden boats and stuff with.
And I want it back. But I know it will seem petty if I go and say "XH I want my Unks hammer"
So, what other small, but very personal thing, do you wish you had taken post spearation/divorce?