If it is a s. I can't really tell but if it is it's not in my washington quarter collection book. It has like a shiny yet glossy look. And a mirror effect to it.
Links usually help.... https://www.cointalk.com/threads/come-look-at-this-a-1994-completely-rotaded-die-cent.325393/ Neat find that looks to have been in the wild for a fair amount of time.
Oh... Just go to the address bar of the page you want to link and copy it. Then simply paste in the same box you type your response in. It's really very easy once you figure it out.
It isn’t uncommon for a person to take a coin from a proof set to plug a hole in a book. Then they are left with an incomplete proof set. Some will put the remaining proofs in 2X2’s or if they don’t have any interest in the other coins.... Simply spend them where they get together with all the other cool coins and say... Hey, let’s go find Shrews!