The Old Court House Museum in Vicksburg has a copy of a reunion photograph of Company A, 1st Mississippi Light Artillery. It was taken in the early 1900s when the survivors were having a reunion in Vicksburg. The Court House also has a copy of a printed souvenir newsletter that the members had made up about one of their reunions. it mentions a lot of the surviving members of the battery by name.
I hope this helps,

Jeff