There is no time frame in the mid-century period in which B&W or grey scale art and professional photography or armature photography (mainly early 60's and later) available for those who had money to decorate said mid-century homes. In fact, black and white photography is very applicable to non modern mid-century/vintage/retro homes. Take your pick on what you choose to call them.
Black and White or Grey scale art go with just about any type of interior design. Color wise that is. Image and and contrast weight are still aspects that need to be considered for each setting.
There is a ton of it available in a huge variety of designs.
Just about anyone who has a camera (of just about any type) and/or a computer can create their own B&W or grey scale art.
Any digital photo can be printed in Black and White if the creator chooses, or if you happen to have the original file.
For me, these are very powerful reasons.
So, here are a few selections I like, and locations to look for B&W or grey scale art for your mid-century, modern or not, home.
white stripes ( and a bit of blue), a photo by DREASAN on Flickr.