Those fantastic Midcentury pattern doors needed hardware to match, and companies like Schlage and Kwikset were happy to provide them. (Both companies are still major door handle manufacturers four decades later.)
The two open-backed designs below are both from Schlage, dating back to 1956: the Manhattan and the Continental, respectively.
Schlage, by contrast, went for the starburst designs, including the two below.
Heavy round designs were also common, simple but massive plates with textured patterns.
And then I've encountered a few that are seemingly unique, elegant patterns of unknown inspiration and as-yet undetermined manufacturer.
Finding these bits of hardware takes a bit of diligence, a lot of peering into the shadows and past the trees and bushes and screen doors. They don't pop out like a spectacular building does. It's rare that a good photograph can be taken from the public right-of-way (once or twice I've indulged in a little benign trespassing to get the shot!), so getting a good capture is all the more rewarding.