The Isaac who was the father of Mary B. HERRINGTON who married Issac DEER was born about 1833 in Jefferson Co., MO, son of John HERRINGTON and Susan JONES, and grandson of Isaac HERRINGTON and Sarah HILDEBRAND on my page at: http://home.netcom.com/~fzsaund/herrington.htmlhttp://home.netcom.com/~fzsaund/herrington.html
Isaac HERRINGTON married first to Mary E. NULL on 10 Apr. 1854 in Jefferson County.Witnesses were Wm. NULL and Jno.NULL, Jr.Isaac HERRINGTON secondly married to Jemimiah -?-, so I do not know which children of his were by which wife.In 1880 he was living in Texas Co., MO.Mary married to Isaac DEER on 27 Mar. 1887 in Ripley Co., MO.
I don't have any additional information on Mary E. NULL, but the place to start would be Jefferson County where she married, and the NULL family had been since the early 1800s.