Fix the tractor: I found a tractor that needs a new wheel to be fixed!
The quest "Fix the tractor" is obtained after the player interacts with the broken tractor located in a secluded field, due West of Yellowfields Campsite. When first interacting with the broken tractor, Flint will exclaim "Oh, The wheel is broken, Maybe I can find another one!"
In order to complete this quest, the player must find a new wheel for the broken tractor. To do this, head Northeast of the broken tractor, near trail marker 10. There the player will find another, different broken tractor. Walk up to the tractor and interact with it's only visible front tire. Doing so will add the quest item "Tractor wheel" to the player's inventory. Head back to the first broken tractor and interact with it again. The "Tractor wheel" quest item will be removed from the player's inventory, the tractor will spring up and become rideable. Interacting with the tractor again will allow the player to drive it, although it can not exit the field. Moving the tractor will reveal a coin that was hiding underneath. Using the tractor to push the bale of hay will reveal a second hidden coin as well.