i often find that the clothes or trinkets i wear end up having special significance to me, moreso than other people. i have specific articles of clothing that seem to make me feel more comfortable and confident in public, and i prefer to wear these whenever possible. so, if i wear anything, its more of a personal comfort thing than actually trying to look a certain way.
i obsessively collect trinkets/jewellry as well, but find that my initial interest quickly fades. these would always get lost, so instead now i like to collect interesting peices of glasswork and keep them around the house. they are much harder to lose.
while i do not actually wear any jewellery nowadays, i do keep a rubber band around my left arm. i like to have it there to play with when im nervous or bored (keeps me from picking nails too) and i tend to be very uncomfortable leaving home without it on. like your keychain, however, when i was a child i went through phases with certain bracelets or necklaces, where i would never take it off, until one day when i just stopped caring and moved on.