When either a home or a piece of property (etc. lawnmowers, tires, even vehicles to some extent) have been left unattended for such a long period of time that nature has finally overtaken the area. This is usually seen in more southern states.
Those worn out tractor tires in Jethro's lawn have been sitting there for so long that they got grassblasted. It looks like you could feed a whole barn full of cows with whats growing out of them!