My keys. I always have them with me.
I have my car and door keys attached to a True utility keyring
There is also a True utility fire stash lighter, a Swiss-Tech utili-key, a Niteize zipit light , a large dog lead clip and a large Bison stash container with a mini survival kit inside.
None of it is expensive but it is all used daily because its there.
I also always carry a Maserin Zuava folder and a Nitecore D11 v2 torch. Again small but used cos they live in
my other pocket.
Two pockets of stuff that can cope with most of what the outdoors (and indoors) can throw at me with a little applied knowledge.