Panax quinquefolius - Ginseng.   What happens for pollination in wild populations in forests appears murky.  Interestingly it blooms in June/July well after almost every other plant has finished blooming.  The literature indicates that its likely to be getting some cross pollination from Lasioglossums and Flies.  I am voting more for the flies.  Photo and specimen by Helen Lowe Metzman.