Chuck, presumably the flag is the "Van Dorn-pattern" flag, which consisted of a red field, bordered in yellow, displaying a silver crescent in the upper left corner, and a constellation of thirteen silver stars in the center of the field. An example is described in a regimental history of the 3rd Louisiana Infantry:

On the 20th there was a review and general inspection, the occasion of unfurling a beautiful battleflag presented by Governor Jackson of Missouri. This flag was made of the finest material. It was red silk, with a strip of yellow silk around the edges. In the the upper left hand corner was a crescent with "THIRD LOUISIANA" worked in it, surrounded by thirteen silvered stars. In the center of the red ground was a scroll in blue, with the words "Oak Hills" and "Elk Horn" inscribed thereon, indicating that the regiment had distinguished themselves on those battlefields. This banner was one of the handsomest in the army, and coming from such a distinguished source was greatly admired by the men.