Okay... On to the serious stuff. I found out that the unripe pumpkin is NOT edible! I don't even know why I thought it was... I hope that this will save you all a lot of hassle :P
The pumpkin goes through 6 stages before becoming the all-wonderful edible fruit. The unripe pumpkin is shown below:
Here is another pic (from the wiki) showing the stages:
Once fully grown, they can be found in patches in forested areas and eaten or crafted into Jack O Lanterns. They can be grown from a seed, but be careful! The water will wash them away (rough time on my farm... accidentally washed away all of my pumpkins...).
It's a good idea to craft some of the pumpkins you don't need into seeds, because each pumpkin yields 3 seeds!! You will be able to grow a lot of pumpkins ;) I've started doing this, and I feel like I'll never starve again! I've got sooooo much food!!
Here are some links you can check out for more info!!