Coralbelle, it's good to 'talk' with you again too.* :)* I hope the winter has been kind to you and your family!* There are several horsechestnuts, but since I think you said it planted itself, I'm guessing it's a native.* Those get even larger.* I don't remember you saying how close it was to the sidewalk, but this one is going to need lots of room.
http://hort.ifas.ufl.edu/trees/AESHIPA.pdf
Newt
When weeding, the best way to make sure you are removing a weed and not a valuable plant is to pull on it. If it comes out of the ground easily, it is a valuable plant.