At this URL is Robert Skelton. He was a member of the 37th Miss Inf. He died 15 Jul 1863 of illness.

For whatever reason, he was mistakenly re-buried in the Vicksburg National Cemetery with the other re-interred Union soldiers when the cemetery was established. As a result of the mistake, he received a Union headstone.

Would you please look at this grave marker and tell me what the symbol is under the soldier's name?

The symbol appears where the soldier's state affiliation should appear.

TIA. /anna
http://freepages.history.rootsweb.ancestry.com/~taleese/soldiers_rest_vicksburg/mississippi/skelton_robert_t/skelton_robert_t.htm