Answer:
Most people throw them away. The turkey head is not the best part of the turkey. The turkey is so big that if you dispose the head, then you have not lost much of the turkey meat. Also, it is a waste to try to get all the extra meat through all of the turkey head organs and the beek.
The manufacturing companies toss the turkey heads and feet into the mounds of turkey/chicken fecal matter. This waste matter breaks down and dissolves the turkey heads and feet.