The 2004 Wisconsin state quarter features the images of an ear of corn, a round of cheese, and a cow, but the Denver-minted 2004-D Wisconsin Extra Leaf High quarter has an error and shows an extra cornstalk leaf, which points upward in its design. This mistake makes the Extra Leaf High style of this coin one of the rarest of the American state quarters.
Another flawed Wisconsin state quarter, the 2004-D Wisconsin Extra Leaf Low quarter, is very rare and can fetch high prices at auction. Like the Extra Leaf High coin style, the Extra Leaf Low quarter features the same artistic design elements, but the face of the Extra Leaf Low has an additional cornstalk leaf that instead points downward. This currency is worth nearly as much as its Extra Leaf High counterpart.
The Minnesota state quarter features images of the state's wildlife, trees, and lakes. Some of the state's quarters show an extra treetop in the coin's design, and this 2005-P Minnesota Doubled-die Extra Tree quarter is considered more rare and valuable if its amount of die-doubling, which makes the extra tree appear more clear, is pronounced.
The design of the 2005 Kansas state quarter features a bison and sunflowers. A die break that affected some of the Philadelphia-minted coins created the 2005-P Kansas Die-break Reverse quarter, which shows either a humpback bison or the motto "IN GOD WE RUST."
When minting a coin, a rotated-die error can cause a mismatch in the currency's obverse and reverse sides. These mistakes are rare and appear in a few state quarter designs, such as the valuable 1999-P Oregon Rotated-die Error quarter.
The uncommon 2000-P South Carolina Off-center Error quarter features an off-center strike because the Philadelphia mint did not properly align a small percentage of the Wyoming state coins with a planchet. A quarter that includes an off-center strike can markedly increase the coin's value.
The Wyoming state quarter minted in Philadelphia features a small number of coins that have a doubling visual effect. This rare 2007-P Wyoming Double-die Reverse quarter shows doubling on the coin's design around its saddle horn image.
The 2008-P Arizona Extra Cactus Leaves quarter features an accidental die-break mistake that makes this uncommon coin differ from the typical Arizona state quarter's design. This makes the coin's reverse side appear to include extra leaves.
A broadstrike can cause a quarter's image to spread out because a mint fails to contain the coin in a collar die when striking it. The rare 1999-P Connecticut Broadstruck quarter can have a high value because of this occurrence.
The 2006-P Colorado Cud Errors quarter is an excellent example of a coin featuring an uncommon cud error. This coin's image features an unstruck area, making the quarter highly collectible.