2011-P ATB Olympic 25c Obverse Clashed Die

You can see clash marks all over the obverse in the fields and throughout Washington's portrait that represent many of the low points of the reverse motif "clashed" into the obverse with the strongest marks below Washington's chin and ear. What is perhaps educational about this coin is that the fact that reverse shows no signs of a clash, which demonstrates that sometimes clash marks do not transfer to both dies during a clash due to the geometry of one or the other die's design or the fact that sometimes the Mint catches the clash on just one die, replaces it and lets the other continue in use.
Die clashes are the result of a failure of a feeder system to deposit a planchet between the dies during a press cycle. When this occurs the dies clash or smash into each other imparting some of each die's design into the opposing die to a greater or lesser degree.
In general, clashed die varieties do not attract the same kind of interest on modern coins that Doubled Dies, Repunched Mintmarks, Overdates, etc. do. However they are a lot of fun to find and collect even if they aren't as heavily promoted and cataloged as the more popular variety types. Nonetheless, that could be changing. Interest does seem to be growing in this area, albeit slow but steady. One group of collectors who may eventually put the stronger and more radical die clashes on the map are the folks that run a relatively new website dedicated to clashed dies here: http://www.maddieclashes.com.
Both coins featured here were submitted by Bill Gladden of Michigan who found several of each of them in original rolls.

See my comments on the Hayes dollar in my previous post.