It's my tree. And I'm absolutely positive it was a birch tree before it turned into this. [links to a picture of what looks like an acacia tree]

No signs to indicate it had been replanted. Grass was fine, fence was undamaged, the trunk wasn't scratched up.

And for reference, here's the yard a few months ago when I had my parents over. [the other trees in both pics can be compared, it's the same yard, and that is indeed a birch tree, along with her parents at a picnic table shh.]