"Our company's patron, Mr. Murry Nelson, of Chicago, had formally, and with some ceremony and a speech, presented us with a costly silken banner, but it was after some time given over to storage and safety. (A gentleman with a better memory than I appear to have had informs me that our flag was with us in the field and used there as a battle flag. Mr. Nelson holds the flag now as a valued memento of the war.)" Francis, Charles Lewis. "Narrative of a Private Soldier in the Volunteer Army of the Unitaed States." William Jenkins and Copmpany, Brooklyn, N.Y., 1879. page 46.
Unfortunately I cannot document which of the three flags shown here might the the flag mentioned.