The only record I found for Mary P Turnbull indicates she died in 1840 in Jackson Co, In. Could this be a daughter instead? This is from a family data collection on Ancestry so may be incorrect.
Name: Mary P Turnbull Parents: John C Turnbull , Rhoda Ann Kitchell Crane Birth Place: Jackson CO, IN Birth Date: 29 Jul 1840 Death Place: Jackson CO, IN Death Date: 15 Aug 1840
It sounds like Rhoda Ann was a second wife. There was two John Turnbulls in Jackson Co. The other one married Sarah Sulivan in 1821.
Name: Rhoda Ann Kitchell Crane Spouse: John C Turnbull Parents: Jonas Edward Crane , AbigailKitchell Birth Place: Hamilton CO, OH Birth Date: 22 Mar 1816 Marriage Place: Jackson CO, IN Marriage Date: 9 Jan 1835 Death Place: Jackson CO, IN Death Date: 29 Jul 1859
Try RAOGK for a volunteer lookup or go to Floyd Co Genweb and see if there is a lookup there.I know there are some cemeteries recorded there.