I have a box that I keep specifically for the purpose of holding such treasures. The box itself is a memory, a prize won in a bridal shower game when my dad’s only sister got married. It’s small in size, pink, and used to be strawberry scented.
Inside are things like movie ticket stubs (a great friend took me to see Serenity; because I’d never even heard of Firefly, he later sent me copies of the set, as well as something like 50 movies (and ALL THE STAR WARS MOVIES! and a bunch of James Bond movies I still haven’t watched like 7-8 years later…)), a gas station receipt I got in southern MN during a treacherous snow storm on my way to meet that same friend, a keychain that belonged to my childhood best friend who died when we were teens and other little things from my time with her, bits of paper from the first time my oldest wrote “mom” and his first name, etc. Related to the OP, I have a piece of notebook paper from more than half my life ago, a score card from when my brother and I decided to play a game of Rummy 500 and kept right on playing every day for a solid month. We played to 10,000 and I won.
I have lost all of these people – my Firefly friend to the mists of time and ridiculousness, or whatever; my best friend; my brother to drugs and general shitbaggery; that adorable and sweet little three year old who put too many lines in the E in his name is long gone, replaced by a 10 year old who gives one armed hugs and wears cologne sometimes – and I guess I sort of put my love for them in this box. I love them all anyway, of course, but it’s in the background mostly, in some distant place that I don’t poke around in every day. The memories are always there when I want them though and sometimes I find things in there that I forgot I had and I spend whole days remembering everything I can about the person associated with the Mystery Object.
That box is the one possession I would grab in a fire.