It's waaaayy better than that
Per the interwebs:
"The collective noun for a group of rattlesnakes is a coil or a rhumba. A group of any kind of snakes can be called a knot, den, pit, nest, or bed of snakes."
Hopefully the OP still has time to edit his or her original post. Should read:
"We saw a rhumba of rattlesnakes on the scout trail!"