I have traced my Alexander ancestor (Milton Alexander, 1822-1899) to Grayson County, TX briefly before he moved on to Linn County, MO. He was Thomas Alexander and Mary Ramy's grandson through Greenwood Alexander. Although Milton Alexander moved most of his family to MO he left a daughter in Sherman TX. Pamelia Jane Alexander married Napoleon Burdine Anderson there in 1861. I have seen deed records for an A.M. Alexander in Sherman but I don't know how he might be related.