Are you sure it is spelled Mathewes?
Didn't have any luck in 1850-1860-1870 census, the UN closed down after Civil War .......
Mount Lebanon was probably the first permanent settlement in what is now Bienville Parish. Its pioneers were Baptistsfrom South Carolina who quickly established a church andschool. The school became Mount Lebanon University in 1853, but closed during the Civil War to serve as a high school and a Confederate hospital. After the war the school reopened. After years of struggling, it was consolidated in 1906 through the Louisiana Baptist Convention into Louisiana College in Pineville in Rapides Parish in Central Louisiana.
Found this on different spelling:
Iberville Parish, LA Plaquemine
George Matthews age 40, 1830, born Mississippi
white male occupation school teacher
wife martha age 37 KY
child Kate age 8