I was leaning towards Marmaduke's men as well based on what I have read of the battle. Oftentimes the taking of flags will not be found in official reports - if you don't report it then the War Department doesn't know you have you so it becomes a nice souvenir instead.

My original source for this was a post-war Iowa newspaper by the way - that the 14th Iowa took the flag.

Thanks.

Greg Biggs