Question: are there any rare bicentennial quarters?
Answer: If you find circulated 1776-1976 quarters either with no mintmark (those were made in Philadelphia) or the "D" (Denver) mintmark in pocket change, they're worth face value – 25 cents. If you find a 1776-1976 quarter with an "S" (San Francisco) mintmark, it's either a proof specimen or a 40% silver Bicentennial quarter.