Need Help Identifying Metal on Drain Plug

I have the same problem, dismantled engine and after many hours of searching I finally found where the metal pieces came from, on the inside of the freewheel clutch are little tabs on the circlip that fit into slots, what has happened is the tops of the slots have broken off!

Good find!

Maybe that is why my sprag and flywheel locked together. These bits likely bound it up.