It isn't an error, on most coins, the Philadelphia Mint didn't get a mintmark until 1980. So your coins were simply minted at the Philadelphia mint and not an error.
$25
All error coins need to be seen. Take it to a coin dealer for an idea of value.
Value depends on what kind of error. please be more specific
CoinTrackers has estimated the 1974 D Washington Quarter value at an average of 25 cents
Not enough information. Please post a new question with a description of the suspected error. Thanks!
It depends on what the error is, please post a new question with more details
This is a rare misstruck error and is worth up to $90.00 according to condition.
$.25 unless it was an error. 2004 Florida quarters are not rare.
State quarter errors refer to the mistakes or variations that occurred during the minting of the U.S. state quarters, which were released from 1999 to 2008. These errors can include misprints, such as incorrect designs, missing elements, or unusual mint marks. Some notable examples include the 2004 Wisconsin quarter with a "high leaf" and "low leaf" error and the 2005 Minnesota quarter with an extra tree. Collectors often seek these error coins due to their rarity and potential value.
Check that coin again. Mint marks were on all quarters by 1981.
The value of a 1971 quarter with an error depends on the type and rarity of the error. Common errors can be worth $50–$200, while rare ones may fetch thousands.
The double die error on the Wyoming quarter is so minute that it is very difficult to see without the aid of a magnifing glass. Errors that have a high value are usually those that are easily seen by the eye. Those like the Wyoming quarter are of interest to error collectors but the public usually has little interest in an error on a coin they can't look at and see it. Since it is the demand for the coin that sets its value, this difficult to see error will probably not have a very high value.