Kitty. There are some eyewitness accounts that state that a small group of Cherokee Indians arrived at the 'Southern' camp prior to the Battle of Wilson's Creek, but I do not think there is any mention of their involvement in the battle in any accounts. I have read modern reports that state Watie might have been an observer at Wilson's Creek, but I have seen no original documentation that backs that up.
Watie's involvement at Pea Ridge is well documented, but the taking of scalps from Union soldiers, so horrified Southern commanders that they were pretty well limited to the Indian territory (Oklahoma) afterwards. The first battle of Newtonia, Missouri is an interesting battle to research, if your interest is in Native Americans fighting in the war. This was one of the few incidents were Indians fighting for both sides actually met in battle.