Mr. Skellie, I found a 3rd MS infantry unit that fought for the Union, but it was made up of colored troops and originated in a totally different part of the state.
I forgot to mention in an earlier post that there is a "J" after Nimrod's name on a family tree. He also went by "Peter" or "Pete", which I have also searched for but haven't found anything on.
By the way, I have pictures of some of these folks' graves at http://www.flickr.com/photos/shar_14_22/.