I found a Frederick J. Nelson, c.1862 born who married a Sissie Jimmerson and lived and died in Senath, Dunklin County, Mo.
Marriage was probably after 1880 because in 1880 he was living with his mother Susan in household of his uncle & aunt Elisha R. and Nancy Harrison. Nancy was Susan's sister.

His children with Sissie were Celesta, William, Stella, Frank, Mollie, Marion and Rufus who was born July 26, 1883 at Carmi, Ill.

Frederick J. Nelson's brothers/sisters were: John, (c.1848 born), William (c.1850 born) Jesse (c.1852 born), Alcie E. (c.1854 born) and Job (c.1857 born)

Frederick W. Nelson was born c.1822 in Monroe County, Ky. and married Susan on March 4, 1847 in White County, Ill.

Susan applied for a pension on March 16, 1863 (certificate #24391) and applied (no date given) on behalf of dependent child(ren) (certificate #66058)