This thread is so old I believe you already have found the answer. Ambrose McKee appears in the census records for 1840. I believe they were in Tennesse as early as 1819 when my great great grandfather James McKee was born in Rutherford County, Tennessee.
I am very interested in sharing information with you. My mother was Cana McKee Wiggins, born in Batesville, Panola County, Mississippi to Cleighlon Short Mckee and Maudie Belle Norwood McKee. Cleighlon's (he was called Cle) parents were Wiley E. McKee and Ella LaGrone McKee, Wiley's parents were James McKee and Lucinda Whitby McKee.
From your postings I surmise that your husband is descended from William T. McKee, who was James McKee's younger brother. They resided for a time in Hardeman County, Tennessee. Their parents were Ambrose and Martha (Patsy) McKee.
Please contact me at firstname.lastname@example.org
if you would like to share information.