Brooke here. I was weeding the Vestigial Lawn and found this:
It is: (a) definitely a tooth; (b) definitely the size of a human tooth; and (c) definitely looks like a human tooth. Whether or not it is actually from a human is beyond my knowledge of disgusting things I’ve found in my backyard. It’s been out there for a while, thankfully, so if there is a corpse still rotting out in the ivy-covered yonder, the dogs would have discovered it long before now and brought pieces into the house to gnaw on. Small blessings.
Flying by night 
Well, it looks like a molar that’s been sheered down the middle, but it’s kinda hard to tell the scale. The root looks too big for a human molar, and the shape is wrong for bicuspids on any large species I can think of. Horse teeth have a much longer cap. Cow’s teeth can be close to a human’s in size, but they have much larger roots than people teeth.
Judging by the amount of wear and tear on the enamel, I’d guess it was a goat or sheep’s molar.
Sasquatch, definitely Sasquatch.
I take back what I said. I showed this to a friend of mine who works for an oral surgeon. Seems herbivores have teeth which are flatter and shaped more like pegs. The molars and premolars are also packed in sideways to get more in there, while that tooth’s widest face is the one which would face outward. That’s also not a breakline. It’s a cavity, which really doesn’t occur that often unless an animal has been digging in people’s trash and gotten away with sugary treats.
A pure carnivore’s molars and premolars are designed for shearing, so the crowns would be more pointed, and one is usually more pronounced than the other.
Apparently that belonged to an omnivore, though not a human because our bicuspids are turned perpendicular to the way that tooth would present in the jaw. That means it’s likely a raccoon’s tooth.
Aw. I wanted to believe it was the Crazy Poet’s tooth.
Wow, that would be the biggest raccoon I’ve ever seen. There’s a new phobia for me, I think. /shudder