Although described in the literature as "regular dies trial pieces", these are actually restrikes deliberately made in the early 1870s and sold as part of complete off-metal sets of the silver coinage of this year containing quarter, half dollar and dollar which had the reverses of 1866 with the motto "In God We Trust" above the eagle.
This coin is struck from an obverse die with the broken "D" in "United" and may be a backdated novodel.
Examples were struck as follows:
Copper J378/P446 with a dozen or so believed to exist.
Aluminum J379/P447 with only 2 or 3 known.
Nickel J380/P448 with only one or 2 known.
Photo courtesy of Heritage.