They sure are moonflowers!!! Have had them in my garden for 50+ years and in my parents garden all of my growing up years. They go through beautiful stages as they open and in the morning the kind of curl back around themselves before finally closing up and drying and then falling off leaving the prickly pod that are "full" of seeds.
The blooms only last for one day, much like the daylily. I did hear in the last year or two that the seeds are a halucigen.