Margaret was the daughter of John Greenfield but her mother is unknown. The date and place of her birth have not been found.
Her husband was Bryan Newcomen. They were married, but the date and place have not been found. Their eight known children were Charles (?-?), Jane (?-?), John (?-c1589), Clara (?-?), Edith (?-?), Mary (?-?), Elizabeth (?-?) and Katherine (?-1583).