This is not my Stegall / Stigall line, but I offer the following.
I have no record of a son J.B. born 1858 for James Buchanan Stigall and Almira Fish.J.B. would be age 2 in 1860 and age 12 in 1870, and there is no such entry on the 1860 or 1870 census for James Buchanan.
I believe your James Buchanan Stigall born 12 Dec 1856 IL, is the son of William T. Stigall (1833 TN – 1862 MO) and Jane C. Sapp (1840 OH – 1864 IL), married 1 Mar 1854 in Fayette Co. IL. I believe that the name "Sapp" for Jane is an adopted name she and her brother took on.They are listed as surname Burrus on a couple of census entries.