I have a very large amount of state quarters. I have them separated by state and was wondering if any of them are valuable? Any errors to look for? Any to keep?
I would suggest getting a Red Book to start with. It outlines the known errors for these and mintage numbers. As for the values though, the best way to check on values is to search completed auction sales, etc, for a particular coin to get a ballpark value on it.
2004 - Wisconsin Leaf Errors. Coins exhibiting these errors came from the Denver Mint. These coins range in value, but currently can fetch $50-100 per quarter. 2005 - Minnesota Double Die & Extra Tree Errors. There are a lot of errors associated with the Minnesota reverse. Values range from $10-300+. 2005 - Kansas "IN GOD WE RUST" error and humpback bison error coins. Values really vary with these errors, but sometimes can reach up to $100. 2008 - Arizona Extra Cactus Leaves. Die breaks caused some extra leaves on the Arizona Reverse. Values vary, but coins are generally sold around $10-20. Other Errors - There are many different errors that have showed up in almost every year of mintage. Some of these errors may include die breaks, off-center striking, planchet clipping, die cuds, grease strike through errors and missing layers. As the market is still fairly young, values for these types of errors will vary greatly but could be worth $5-300+ depending on what you have. http://joemacho.hubpages.com/hub/Value-of-State-Quarters
Here’s a link to Wexler errors. Other than the errors and high grade uncirculated, most business strike state quarters are worth face value. I just cashed in most of mine to buy the “New State Quarters”, the AtB’s, which have much lower mintages. http://doubleddie.com/179401.html
