Definitely not what we call pig weed in the south. What is called pig weed here is a type of amaranth.Pic is I bit blurry but from I’m seeing, that looks like pigweed or similar. I spend a lot of time on this old farmstead every summer pulling it by hand.
I hope that you have something easier to deal with; at least I don’t have to worry about snakes!
if you have a country extension agent take a chunk and ask them,