The 2nd Rhode Island was the very first regiment to be engaged. It could be the 2nd Rhode Island. Maybe they lost a flank marker. It was a very confusing day with many different flags and people wearing the same clothes.
The 1st Michigan lost 1 flag, I saw that on the Michigan flag website. They had a picture of the flag that was captured. It was dark blue and looked like their regimental flag.
General Evan's OR report was that Wheat's Battalion had captured a "stand of colors".
Have a good day,