Parts are mostly just tools to me and it is indeed only the ones with memories attached that stick around.

I have a stem spacer from Sea Otter Classic 2006, when my generous grandparents flew me out there for my 16th birthday. I raced the DH on my hardtail and got to see the premiere of Seasons - a dream come true at the time! That 10mm spacer is something I won't let go easily, though it's not on my current bike because the colour clashes.