I asked Scott Ogden to sort it out for me and
took notes so you'all can go relabel your pots. The giant prairie
lily, Zephyranthes drummondii (aka Cooperia pedunculata or
Sceptranthes) has very broad grey leaves, perhaps the broadest leaves
of any Zephyranthes so it is easy to ID on sight. It flowers most
often in the spring. The other common rain lily from this area is
also white night flowered (probably shares a pollinator) but it has
narrow, more typical leaves and is properly named Zephyranthes
chlorosolen (aka Cooperia drummondii). It flowers most often in the
fall but both species will flower together, especially in summer. I
hope this clears up some confusion, it did for me.