This is a terrific find for a metal detector and might just be priceless as a souvenir. However, it is a common date within the Seated Liberty quarter series. This piece would almost certainly be flagged as a "problem" coin with environmental damage by PCGS. Even if it were a problem-free VF the value would not justify spending the money to have it graded.
I say just enjoy the coin. Better yet, go back to the site and see if there are any more out there! Maybe you'll find a rare date for which certification would be appropriate.