Native Americans fought in quite a few battles as regulars (and with non-Indian troops) including Newtonia, Pea Ridge, Prairie Grove, Honey Springs, Neosho, Poison Springs, Ft Wayne, 1st & 2nd Cabin Creek, and Massard Prairie.
The Cherokee Confederates that took scalps at Pea Ridge (Leetown) was probably Drew's Regiment (1st Cherokee Mtd Rifles) who defected in July 1862 and became the 3rd Indian Home Guard (Union Indian Brigade). Members of this unit also claimed 'credit' for the killing of Confederate wounded at Pea Ridge (which was blamed on German troops at the time) as evidence of their loyalty to the Union.