Dutch elm disease kills primarily American Elm, so this could be another species. In American Elm trees often survive to seed producing age, but later succumb to the disease. There are also disease resistant hybrids being planted and they may also be seeding around their immediate area. HTH Chris

Anything with thorns wouldn't be poison ivy poison sumac poison oak. That being said have you tried Benadryl to calm the itch? It may be simply that you're allergic to one of the planta or something in the area.

I looked at pictures of Partridge Berry on the Internet and I am pretty sure that is it. The description also matches. We have woods near our house, but I never see it there. I suppose some visiting birds enjoyed eating the berries at some point. Now to figure out how to get rid of it!

A closer shot of the leaves would be better. But just from the general growth habit and shape one candidate could be Clerodendrum bungei.