Ellen was the daughter of Biddy Mason. She was an African American child enslaved by Robert M. Smith, who took her to Utah.
The 1850 Census was actually taken in 1851.
1900 Census states that Ellen was born October 1842.
Delilah Beasley's book, The Negro Trail Blazers of California, cites a family bible that states that states Ellen was born 15 October 1838. Indirect sources including censuses and Ellen's death index infer different years of birth.