As a personal working rule, I normally use a magnetic tray to collect all the bolts, nuts, washers and stuff from the disassembling and there they where at the end of the job!!!!
But I might have mixed stuff up...now I’m starting to doubt...I’ll go to the dealer, very good point! Let’s just hope they don’t ask where I took them from.
SORRY, but I am still laughing bout that... taking them to a parts counter, and asking that young service fellow will likely get you a look, and comment like "HUNH??? I dunno...." as he looks at you like a deer in the headlights...
as I said, I actually did go thru the microfiche... even though I know it's not from the bike... and can safely say they ain't from your bike.... some other project... they look like roller slide parts from a drawer assembly...
they surely aren't rotor buttons, and as you noted you only messed with the rear brakes, which have NO rotor buttons... ain't them...
the part that throws me off is the 7 quantity.. toss them in a bag somewhere, and forget about them until you remember where they
REALLLLLY came from.