Charles,
Not much is known of the 28th Louisiana's flag. What is known is that the
regiment was authorized to place the battle honor "Chickasaw Bayou" upon their colors.
It is also known that the unit tore their flag into pieces and distributed them to the surviving
members in May 1865.
The Trans-Miss sector was a hodge-podge of organizations and flags.
If one were to guess as to the nature of the 28th's flag; I would say that
the first national or battleflag pattern would be the best bet.

Ken Legendre