I'm referencing an old book from 1961 that I picked up at a flea market. It's called Wildflowers of North America in Full Color, by Robert S. Lemmon and Charles C. Johnson, published by Hanover House.
Wouldn't you know, the first picture is actually an easy ID- I started at the back of the book (that's how I read magazines and similar publications- for some reason I always start at the back) and the first flower I need to ID is right there- the Cardinal Flower:
Here are some pictures of different stages of Groundnut Flowers:
This one is a mystery to me, although I feel like I saw it in the Audubon Field Guide (*UPDATE: this is Buttonbush- thanks Pete for the tip):