Marilyn,
Drew's Regiment Cherokee Mounted Rifles, also known as the 1st Cherokee Mtd Rifles, no longer existed after July 1862. The regiment defected en masse after the debacle at Locust Grove, Cherokee Nation. The men of this regiment made up about half of the 2nd Indian Home Guard (Union) and all of the 3rd Indian Home Guard. The 3rd IHG was known as the "Pin Regiment".

The two Cherokee Confederate Regiments that were organized in 1861 (Drew's and Watie's) both claimed the title "1st" Cherokee Mounted Rifles. To avoid conflict and confusion, it became common to refer to them as "Drew's Cherokee Mtd Rifles" and "Watie's Cherokee Mtd Rifles" or just Drew's Regt and Watie's Regt. A variety of names are used in official documents but generally Watie's Regt is known as the 1st Cherokee Mtd Volunteers -- with Drew's being known as "mounted rifles". Adair's Regt became known as the 2nd Cherokee Mounted Volunteers.

I hope Robert knows some specifics on the type of pins used. I have them pictured like straight pins but larger than modern pins used for sewing etc.. All the contemporaneous references I have seen just call them "pins" as if everyone would know exactly what that means -- that is, a common household pin. I just don't know what a common, readily available, pin of the 1850-1860s looked like.