Welcome to CoinTalk! It looks like a normal 1979 clad quarter that has seen some wear and been in environments that caused it to look rather unappealing. I'd say it is worth a quarter. My children would say it's worth a gumball.
Not to beat you down much but it's just corrosion and circulation staining. Pareidolia. Worth 25 Cents U.S . Maybe a gumball for sure, love it!
