State Quarters are legal tender. So they are redeemable for $0.25. If they are certified in a holder (PCGS, NGC, Anacs, ICG MS 65/66) they will likely be worth more than face value (although the premium for most still won't be high...basically the final price does not even justify grading the coins). Looking at completed ebay sales, most MS 65/66 examples sell for $1-$5.
I doubt these are worth more than 50 cents each even in this condition. There's really no market for these. These coins were heavily over produced and everybody has them. The S coins, proofs, silvers and any low mintage coins in this series would be more desirable. Just my 2 cents.