The Mormon religion - also known as The Church of Jesus Christ of Latter-Day Saints was founded by American Joseph Smith in the 1820's. Smith - who had previous convictions for being an imposter (he had claimed he could use a special stone to see where gold was buried) - claimed an angel had told him where to find buried 'golden plates' which told the story of an ancient people. Smith then dug up the plates and using his 'seer stone' translated the plates, culminating in the Mormon bible: The Book of Mormon.
The book told the story of a cohort of Jews in 600 BCE sailing to America and becoming the forebears of the Native Americans. A resurrected Jesus appeared to them and they wrote their story on these Golden Plates which they buried in upstate New York. They were later found by Smith with the guidance of the Angel Moroni. Of course the plates were taken back to Heaven by Moroni so no one outside the church could confirm any of this.
Smith gathered many followers but faced severe religious persecution from 'normal' Christians, having to move his flock ever westward to find somewhere safe. After he was killed in a gunfight in Illinois, his successor Brigham Young trekked across the Great Plains in the 1840's to found Salt Lake City and the territory of Utah as a homeland for Mormons. Eventually to gain statehood the church had to give up polygamy and ceede authority to democratic institutions. The church has grown to now count around 16 million adherents of some sort or another - some sects still practicing polygamy. They are a highly evangelistic religion, sending their young people around the world as missionaries.