But it was a substantial body and not likely to break or wear out, and when it was dressed the clothes covered much of its roughness.

The head of Jack Pumpkinhead was, as you have guessed, a ripe pumpkin, with the eyes, nose and mouth carved upon one side.

The pumpkin was stuck on Jack's wooden neck and was liable to get turned sidewise or backward and then he would have to straighten it with his wooden hands.
The worst thing about this sort of a head was that it did not keep well and was sure to spoil sooner or later.

So Jack's main business was to grow a field of fine pumpkins each year, and always before his old head spoiled he would select a fresh pumpkin from the field and carve the features on it very neatly, and have it ready to replace the old head whenever it became necessary.

He didn't always carve it the same way, so his friends never knew exactly what sort of an expression they would find on his face.