I believe the "PTO" owns them. We are incorporated so the corporation is the owner. If at some point we disband we could vote to donate the stuff to the school.
d

Equipment that the PTO purchases for uses at the school - popcorn machine, upright freezer for Market Day, button maker, etc.

Who do those actually belong to?

There is an ugly debate brewing about the assets belonging to the school and not the organization so they can do with them what they wish.