Pumpkins tend to go hand in hand with Halloween, especially where the Jack O' Lantern is concerned. The Legend of Jack O' Lanterns started off not with pumpkins actually, but with a despicable drunken bastard named Stingy Jack.
While making Jack O' Lanterns is a old custom, we have Stingy Jack to thank for it. This Irishman was known for pulling pranks on people, and apparently pulled them on everyone, including the Devil himself! And if you know anything about the Devil, he doesn't take too kindly to practical jokes at his expense. You don't want to catch the attention of the Devil, because in the end, you'll end up the butt of the joke.
One time the Devil got tricked by Stingy Jack to climb into an apple tree. Once he was there, Stingy Jack put crosses all along the base so the Devil was stuck, forcing the poor bugger to promise not to take his soul when he died! What a jerk right?
"Sure," the Devil said, but Stingy Jack didn't pay attention to the tone in his voice. Or the twinkle in his eyes, "I won't take your soul Stingy Jack. Now let me out of this tree or I'll throttle you!"
Stingy Jack thought he had won. But he didn't realize there are worse fates than even going to Hell.
So years later, when the old kook finally drank his last whiskey, he died and went to Heaven. Of course no one in Heaven let him in. He was a bastard! They told him flat out he wasn't invited to their fancy parties, and kicked him to the curb. He was forced to go to Hell, but he had made a deal with the Devil, and the Devil always pays his debts. So when Stingy Jack arrived, the Devil merely smiled darkly and said, "Sorry, no room at the inn boyo! I guess you have no where to go now huh?"
Stingy Jack didn't realize what he had done. Didn't realize he just damned himself to be a homeless vagabond of a spirit, forever trapped between the realms of Heaven and Hell. Trapped in eternal darkness.
"Not so smart now are ya," The Devil chided, and tossed him a candle, "Here, use this to light your way. That's the last gift I am giving you."
Stingy Jack had no choice but to accept the candle, and as he wandered, he found a small turnip in his path. Deciding he needed something to hold his light in, he put the candle inside and used it as his lantern. The cheap loser wouldn't even buy a real lantern, so he just made one out of food stuffs.