Are you sure that's a pumpkin?

It doesn't look like a pumpkin and it looks like something has been gnawing on it.

It looks like a squash of some type. Do all the fruit on the vines look like that one? It may be a squash that should have been used by now, maybe?

not a Pumpkin ? some more pics of smaller fruits that have just started

Sorry I don't know more about the different varieties of pumpkins, but I looked up "round yellow squash" and "yellow pumpkins". Here are pics of the 2. What I'm noticing is that your stems are yellow, which are like the yellow pumpkin image, whereas the yellow round squash has a green stem. Where did you buy your seeds? What was it supposed to look like? If it is, indeed a pumpkin, ....getting back to your original question.............I don't know what's wrong! haha Have you been putting the one with the damage on those wood slats all along? If so, was the damage on the bottom? There are lots of rodents/animals that like to chew on garden things. Sometimes they chew a little, and it doesn't taste so good, so they quit. Do you have a fenced-in garden? what kind of animals do you have around there? Are all your pumpkins showing similar marks? Sorry for so many questions! First pic is of the yellow pumpkin. The 2nd is of the Tatuma squash.