The Kinderhook Plates were a set of 6 small, bell-shaped pieces of brass with strange engravings discovered in 1843 in an Indian mound near Kinderhook, Illinois.

Designed to appear ancient, the plates were in fact a forgery created by three men in Kinderhook who were hoping to trick Latter Day Saints or Mormons, whose headquarters at the time were in nearby Nauvoo. According to Latter Day Saint belief, the Book of Mormon was originally translated from a record engraved on Golden Plates by the ancient inhabitants of the Americas.

The forgers intentionally "discovered" the plates in the presence of a Mormon neighbor, who took them to the Mormon prophet and church founder, Joseph Smith, Jr. According to Smith's journal, he had begun to "translate" the writing on the plates, but with his assassination in 1844 and the subsequent removal of most of the Latter Day Saints from Illinois, no translation was ever completed or published.

The Kinderhook Plates were presumed lost, but for decades The Church of Jesus Christ of Latter-day Saints published facsimiles of them in its official History of the Church — pointing to them as a proof that ancient Americans wrote on metal plates. Although, the forgers came forward and signed affidavits concerning their role in the hoax, apologists for the church denounced their story and argued that the plates were genuine.

In 1966 one of the Kinderhook Plates was recovered and tested. The tolerances of its metal proved consistent with the facilities available in an 1843 blacksmith shop. The tests were deemed conclusive and today there is general agreement that the plates were merely a hoax.