When Mary Polly Sellers was born on 16 November 1802, in Lancaster, Garrard, Kentucky, United States, her father, Samuel Sellers, was 35 and her mother, Sarah Ellis, was 19. She married David Wason McCaslin in 1820, in Lancaster, Garrard, Kentucky, United States. They were the parents of at least 4 sons and 2 daughters. She lived in Franklin Township, Johnson, Indiana, United States in 1860 and Indiana, United States in 1870. She died on 20 September 1871, in Johnson, Indiana, United States, at the age of 68, and was buried in Franklin, Johnson, Indiana, United States.