There should be "dropped" and "placed" on the street for machines (feeders, collectors, stills, sticks, icons, etc). Dropped means other people can take them, Placed means they are locked to the street.
In addition, there could also be an option that can be selected that placed machines can be either just be used by friends or by the general public.
Trees should not be able to be poisoned by anyone but the street owner and animals not be able to be taken or renamed by anyone but the owner. Of course they can be harvested by others. :)