UPDATE 4/12/09: When I found the tire yesterday evening, I rolled it out onto the sidewalk and left it there. I had a hunch about my weird neighborhood, and I was totally right. This morning? The tire was gone...!
I've found a lot of weird things in the shrubs that surround my property - toys, clothes, dirty diapers, hypodermic needles, bottles, food, balls. A 19” TV.
But I think today's find tops it. I went to turn on the water faucet on the front of the house, which is hidden behind some shrubs, and as I leaned in, I saw this:
It's a tire. A big one. That appears to have rolled straight from the road into the shrubs and come to rest against the porch.
I'm assuming somebody would notice that they lost their wheel....
Anyway. I was turning on the water to wet down my garden, which I just finished prepping for planting tomorrow! Here it is, new and expanded!

You can't really tell, but at the far end of each of those rows is a blueberry bush. I planted them last fall & they seem to be thriving! Yay!