March was not married to Samuel Richards (there is no documentation to this effect--this Samuel was married to Mary Chocke), all documentation from land records, etc., shows her married to a Thomas Richards most likely from Charles, Prince Georges or Calvert Counties, Maryland. She did not marry an Englishman Thomas Richards found on many internet trees; in 1736, Thomas, husband of Mary Hoye, became the guardian of Margaret Hoye, Mary's younger sister.
http://msa.maryland.gov/msa/refserv/quickref/html/photodup.html
PRINCE GEORGE'S CO. (Court Record) W, p. 56 Margt: Hoye chooses Thomas Richards to be her guardian, June Court 1736. [1-20-8-29]. 03/31/87. Tracking No.: 18023. PD No.: 87 2028.