My neighbor has a few bushes of these large trumpet-like flowers. I didn't do a good job of including perspective in these photos, but the blossoms are about 6 inches long, and four inches wide.
They are a very pale pinkish color, with yellow ribs, and seem to be a popular subject for local artists, as I see watercolors and oils of them everywhere. They're quite stunning, and I've never seen anything like them before. If anyone can provide an identification of what they are, I would appreciate it. Not knowing their name won't prevent me from driving by my neighbor's house to admire them every evening, though.