The Myers-Mason-Bailey family papers are made up of correspondence, military records, invitations, and ephemera pertaining to Mordecai Myers; his wife, Charlotte Bailey; and their descendants. Much of the collection is housed in four large bound volumes compiled by Cassie Mason Myers James (also known as Cassie Julian-James).
The Correspondence series (52 items) contains incoming letters to members of the Bailey, Myers, and Mason families throughout the 19th century. A group of 18 items pertains to the military service of Mordecai Myers, a captain in the 13th Infantry Regiment during the War of 1812. Most of these concern supplies, orders, and other military matters related to the war in northern New York. Myers received personal letters from his son until the early 1840s. Additionally, the series contains a sheet of manuscript poems dated March 25, 1820, and April 12, 1820. Other items include letters to Sidney Mason from his brothers and letters by Theodorus B. M. Mason about his service on the Pensacola in the mid-1870s. Later items also pertain to Theodorus Mason's naval service.
The Military Orders series (15 items) relates to Mordecai Myers and the War of 1812 in New York. The orders mention troop movements, courts martial, and regulations. An undated return for Mordecai Myers's regiment is also present.
The Invitations, Receipt, Valentine, and Ephemera series includes invitations, programs, and other items addressed to members of the Mason family and to Cassie James. Many items are invitations for James and other members of her family to meet prominent political individuals, such as international ambassadors and members of the United States Cabinet, in the 1910s; one card invites "Lieutenant Commander and Mrs. T. B. James" to a reception hosted by William McKinley and his wife at the executive mansion on January 25, 1899. The receipt documents Sidney Mason's subscription to the American Jockey Club (September 20, 1867). Some items enclose newspaper clippings.
Cassie Mason Myers James compiled 4 volumes of Miscellanies Relating to Theodorus Bailey Myers , her father, in the early 20th century. The books contain correspondence, documents, photographs, publications, newspaper clippings, obituaries, visiting cards, ephemera, family trees, and other material related to various members of the Myers family, including Mordecai Myers, Theodorus Bailey Myers, and Theodorus Bailey Myers Mason. Much of the material is comprised of personal letters between family members, including letters from Theodorus Bailey Myers to his wife Catalina and daughter Cassie, and letters from Theodorus B. M. Mason to his sister Cassie, mother Catalina, and wife Edmonia. Passport documents for Catalina Myers and Cassie Mason James, dated between 1871 and 1897, appear throughout the fourth volume. Other items pertain to the Myers' and Masons' service in the United States Army and United States Navy throughout the 19th century, including participation in the War of 1812 and the Civil War. The photographs, which include formal studio portraits, outdoor photographs, and photographs of paintings, show family members, interiors and exteriors of residences, gravestones, and memorabilia.