An example of J2116/P2082 the Martha Washington quarter, has been discovered in private hands and purchased by Michael Byers, uspatterns.com member #88. It was purchased along with an example struck from one cent dies with this same design on a copper coated zinc planchet. For more on this, click here.
It is likely that this piece was struck outside the Mint from one of the vendors the Mint gave these dies to. Among the possibilities include IDX Inc, PMX Industries and the Olin Brass Corporation.
So far, it is the only one known in private hands. The Smithsonian has 6 examples 3 of each embedded in 2 blocks of lucite. To view one of these blocks, click here.
Photo courtesy of Michael Byers.