Goodness knows why, but Jarvis is in love with the lawn mower. Maybe it's the wheels, maybe it's the 'brroom brrroom' sound, maybe it's the fact that it's always covered in grass. Who knows.
Mow-Mow (as he has affectionately dubbed it) currently lives outside the front door, as this avoids us having to leave the safety of the closed in yard & visit it in the carport. When Mow-Mow is parked outside the front door, Jarvis can visit as much as he likes, sit on it, and pretend he's off to conquer the world.