Thanks, Gary.
I notice you don't show Ben in the 1870 census and here is the problem. Look at the 1870 census for James Twp, Stone County, MO. Look for the name "Prater". You will find Ben, Mary Ann, George A. and little Martha L. age 1. The birth place of all are correct, but the birth place for George A. is shown as Arkansas.

I have a theory as to why they are in Arkansas, but it hinges somewhat on George A. being born in Arkansas, rather than Texas. Do you have any way of confirming his birthplace?

Thanks again for all your help.
Paul