This is the grave marker for Tandy S Nicholson, Company D, 23 Mississippi Infantry, Confederate States of America. It's located in Oakland Memorial Park in Terrell. The same resting place as the British Pilots who died while in training.
I found a posting from a few years ago from someone looking for an obituary for Tandy Nicholson, who was a Civil War veteran. I hope they were able to get what they were looking for.