I honestly don't know of any. I was thinkin' speared Bison, but that's '05. Maybe @Paddy54 or @cpm9ball knows.
I don't know of any errors reported for the 2006 "Return to Monticello" nickels. I have more than 3,000 uncirculated business strikes in Mint bags and rolls that have never been searched, and they'll stay that way until someone reports a major discovery. I could care less about getting credit for any discovery. That and $1.05 will still only get you a cup of coffee at 7-Eleven. Chris