I submitted this very rare mint error or pattern to NGC. They authenticated and certified it as a 1866 $2½ Liberty struck on a 3 Cent Nickel Planchet. According to uspatterns.com, there are five known, and were either deliberately struck for sale to collectors or are mint errors struck on 3 Cent planchets.

In addition to being a very rare mint error or pattern, the controversy of which designation is correct adds to the mystique and allure of these off-metals.

From the USPatterns website:

J542/P607 The regular dies trial piece struck in nickel. These were either deliberately struck for sale to collectors or are mint errors struck on 3 cent nickel planchets. We can account for the following examples: 1) Parmelee-NY Coin & Stamp 6/1890, Reed-Durham Museum – ICG62 2) Heritage 8/99 ANA as PCGS66, Simpson-Heritage 11/20 – PCGS67 3) Stacks 8/76 ANA, Fairfield-B/R 10/77, Byers-Heritage 4/15 as NGC66, StacksBowers 5/16 – PCGS66 4) Merkin 3/68 5) MTB in 1974, T.R. Walsh, per Pollock, possibly the same as #2 or #4 The Mike Byers coin has been authenticated and certified by NGC as a MINT ERROR. It was struck on a 3 Cent Nickel planchet and graded Mint State 66 as shown below. It is unclear, at this time, what the true status of these pieces really is. Photos courtesy of Mike Byers.