The following is a reverse die trial in white metal for J1615/P1811.
This is an interesting piece as the blank side is fully dentilated like on some 1850s cent patterns which were originally in Appendix A in earlier editions of Judd but have now been properly placed in the regular series since those items shared the dentilated side of the gold dollar pattern J136/P163, ie they were struck from 2 dies. It is actually a one-sided proof, the design side has full proof surfaces while the dentilated side looks like a business strike and it was struck using a reeded edge collar. It probably should be reclassified as J1616A.
It is ex Farouk, Kreisberg-Schulman 2/60, Heritage 1/15 FUN, Saul Teichman. It is likely the piece misdescribed as 1879 Obv Blank. Rev. Same as A.W.1597 on page 83 - part of Woodin's exhibit - of the 1914 "American Numismatic Society Exhibition of United States and Colonial Coins".
Photo courtesy of PCGS.