As much info as there is on the internet, I still think walking around mid-century neighborhoods and checking out houses and looking inside actual homes when you get the chance (visit duting estate sales, open houses, etc) is one of the best ways to find the authentic details that put the finishing touches on a mid-century home.
For example, this mid-century mailbox:
Which is on one of the most unassuming homes in my neighborhood. I walk by this house once a week and haven't noticed the mailbox till now. And it might be the best mid-century mailbox that I've ever seen. And I don't think I've ever seen it on the internet.
It would have been too small for our home, but it looks really good on the home it's on.
(Please ignore the junk hanging on the door. I feel weird enough taking photos from the sidewalk. I'm not going to stage a shot but taking things off of people's doors.)