After the Korean War my folks bought a small farm, and my father bought a used Ford 8N, which he used to plow, disk, plant, cultivate, and harvest about 16 of the 20 acres. I don't remember at what age I was first allowed to drive it, but probably somewhere in the single digits. /forums/images/graemlins/laugh.gif
BUT... My first tractor experience was one day shortly after moving to the farm, when my grandfather came out from town to help out with a "really big tractor" that he borrowed from someone. It was an Oliver, although I don't know what model. I finally got a chance to drive an Oliver last summer (a Row Crop 77) in a parade at the local fair -- a beautiful restoration done by the son-in-law of the fellow who now farms thse same 16 acres for us.
My wife and I have the little farm now, including the 8N, so I still have my "first tractor"! /forums/images/graemlins/grin.gif