I have seen the head try to bite even after it was cut off. One year when my son was young, I took him deer hunting and we killed a huge timber rattler. I hunted a stand close to him so if he killed one I would hear it. I think he played with that snake most of the afternoon. It had no head as I blew it off and cut it clean. he wanted to take it home and skin it. he still has the hyde on a board.
Anyway on the two hour trip home that night after the hunt he fell asleep with the snake in a bag on the floorboard between his feet. I knew he was thinkin about the snake, so I eased over and pinched him on the side and good lawd he like to busted out of the truck. I laughed so hard I had to pull over. That snake was probably six feet long.