I hope this helps. Please check the sources to make sure this is your Thomas.
According to Illinois Statewide Marriage Index 1763-1900:
Thomas Ferguson m Rebecca Murphy 12/20/1865
1850 census Greene County Illinois page 47B
623 James L Ferguson 39 Farmer Tenn
Elizabeth 37 Tenn
William G 17 Tenn
James W 16 Ill
Mary Jane 14 Ill
Harris B 12 Ill
Elizabeth L 10 Ill
John A 9 Ill
Ann M 7 Ill
Thomas L 6 Ill
Jonas W 4 Ill
Nancy E 2 Ill
1850 census Greene County Illinois page 56
Levi Murphy 29 Farmer Tenn
Martha 29 Ky
Nancy 11 Ill
James K 5 Ill
Rebecca 3 Ill
Lucy 3 Ill
Mariah 1 Ill
Sorry I could not go further back but this may get you started.
Yvonne Simpson

Looking for info on John Ferguson m Eva Hahn in Greene C Ill in 1830s.
Believe his father was James Ferguson
Siblings: Edward Ferguson m Sarah Chaney, William Ferguson and possibly Catherine Ferguson m Samuel Philips both b in Greene Co ill but married in Collin Co Texas
Edward died in Greene Co. John and Eva migreted to Texas about 1850 and to Ft Smith by 1870. They lived next to EP and Susan Clark in Upper Twp in Ft Smith. Need help on this family desperately. Catherine was my gg grandmother.

Thanks! Yvonne