Cousins was a member of St. Mark's Episcopal Church, the Authors Guild, the Texas Institute of Letters, the Philosophical Society of Texas, the San Antonio Conservation Society, and a trustee of the Wildflower Foundation.
[1] Some of her works were published under the pseudonyms William Masters, Mary Parrish, and Avery Johns.
[4] Cousins began her literary career as an apprentice with her father's pharmaceutical journal after graduation from college.
[2] Cousins wrote over 200 short stories, including "The Life of Lucy Gallant," which was adapted into a Paramount Pictures film in 1955.
[1] Some of her other notable works include:[1] Uncle Edgar and the Reluctant Saint (1948) Ben Franklin of Old Philadelphia (1952) We Were There at the Battle of the Alamo (1958) Thomas Alva Edison (1965) A Christmas Gift (1952) Traffic with Evil (1957) The Boy in the Alamo (1983) In addition, Cousins also edited the anthology Love and Marriage (1961) and the memoirs of President Lyndon B. Johnson and First Lady Lady Bird Johnson.