According to Latter Day Saint history, seer stones were stones used, primarily (but not exclusively) by Joseph Smith Jr, to receive revelations from God.
Smith owned at least two seer stones, which he had earlier employed for treasure seeking before he founded the church. Other early Mormons such as Hiram Page, David Whitmer, and Jacob Whitmer also owned seer stones. Seer stones are mentioned in the Book of Mormon and in other Latter Day Saint scriptures. James Strang, who claimed to be Joseph Smith's designated successor, also unearthed what he said were ancient metal plates and translated them using seer stones.