The Irish used which vegetables to make the original jack-o'-lanterns?

Jack-o'-lanterns and Halloween has been around for centuries. An Irish myth about a man nicknamed Stingy Jack is where the practice originated. The story speaks about how Stingy Jack invited the Devil to have a drink with him. Stingy Jack isn't known for paying for his drinks, so he convinced the Devil to turn himself into a coin. Once again, Stingy Jack doesn't pay for his drinks. Instead, he put the cash in his pocket next to a cross. The Devil is now unable to return to his original form.

After some time, Jack freed the Devil. With the condition that the Devil could not claim his soul and had to leave him alone for one year. The Devil came around the next year, and Jack tricked him into climbing a tree to pick some fruit. While he was climbing the tree, Jack carves a cross into it, making the Devil stuck in the tree. Jack demands that the Devil does not bother him for another ten years, or he will stay stuck in the tree.   

Jack dies, and God would not allow such a savage man as Jack is into heaven. The Devil is still upset about the tricks Jack played on him. He also wanted to keep his word about not claiming his soul; he would not allow Jack in hell. Instead, the Devil sent Jack off into the darkest night with nothing but burning coal to light his path. Jack put the hot coal into a carved-out turnip and has been roaming Earth ever since. The Irish began to refer to this ghostlike figure as Jack of the Lantern, and then, simply Jack O'Lantern.

The Irish and Scottish folks started carving scary faces into turnips and potatoes and would place them in their window seal or near the front door to frighten away the warding spirits of Stingy Jack. The English soon followed by carving faces into beets. Once the tradition made it to America, they found that pumpkins make a perfect jack-o'-lantern.