Did you save those seeds? That is what happens when seeds from a pumpkin are cross pollinated with an ornamental gourd. I actually picked one today though it wasn't nearly as bumpy. One neat thing about them is that, in my experience, they dry and don 't simply rot away. If you like to save seeds and don't want to see more of those you should look into hand pollination. If you bought those seeds I wouldn't buy that brand anymore.

Thank You for the information.
I did not start them from seeds, I bought 2 in. plants and I am not growning any gourds. Whatever happend started at the nursery.
I grow my pumpkins for Halloween yard decor so even thou I can't carve them (maybe I can?) they will be a creepy & fun addition!
I will save some seeds just to see what happens next year.