Great find and nice pictures! I found a breeding ball of garters acouple days ago, it was awesome there was about nine garters, I disturbed them and the small males started to disperse, and I saw the medium sized female they were all around, she looked like a hypo. I could have captured her but I was decided that I would let nature take place. I didn't have a camera this time.
Did you disturb them at all or just watch and take photographs? Im not sure if it is unethical to disturb a breeding ball.