I believe I have some news for you. I have done extensive research on the McGinnis Family of Dyersburg TN. I am a great grandson of Walker McGinnis -- the son of John M. McGinnis (James was the brother of John M McGinnis and the son of John S and Martha McGinnis).
I have created a detailed biography of John M McGinnis (and family) at this web site: http://www.vizualstorm.com/jc/web-content/index.html
Please see it and let me know what you think