I don't think this lives under the seat.
If'n I had to guess, I'd say it was a bronze bushing, maybe the swing arm? spacer for motor/trans, rear wheel spacer, brake pivot assembly? I don't think trans, motor cuz more than likely they were assembled SOMEWHERE else and put on the bike as a unit?
Yep, you'll learn to check the "quick" things first.
Looks like you got a "extra part".
Here's my "Stupid Moment" on the road side.
I had stopped with my '09 Military at a store, (had the bike like 2 days).
(Now this is my 3rd R.E., so I'm pretty familiar with the "usual mishaps"). FIRST MISTAKE- I THOUGHT I knew what I was doing!!
Hop on the bike, I ALWAYS fire my bikes up whilist I'm putting my gloves, helmet , etc. on, to let it warm up
I hit the E button-crank, crank, crank, crank,(don't panic, it's a new scoot, just learn it's starting procedure), choke, crank, kick, kick. Check the gas, open the filler cap, yet gas in there.
"WHAT THE F***"!!
Start ripping it apart, fuses, head light, connections all over, looking for SOMETHING.
Put it up on the center stand, more tinkering, try it again "Huston we have IGNITION"!
Then it hit me- I HAD THE @#%&^()**()&&^^%$#@#!!@#$%&^*(&()*)(*!!! SIDE STAND DOWN!
Spent like 2 hours there, had my wife run me over a bunch of tools, was pissed to the max for purchasing a bike that quit after 200 miles, had to put up with my friends verbal abuse, my wife's "THE look"!
That's my "Dumb Sh**" story!
So don't feel bad, you gotta put your dues in if'n your a R.E. rider!
Welcome to the club!!
Joe
I ride, therefore I am!