First off, I just wanted to thank you all for all the work you've done at giving these works new life -- I've greatly enjoyed listening to a lot of what you do.
Secondly, I wondered if y'all were aware of this recent exploration in public domain works: https://boingboing.net/2019/08/01/80pct-pd.html
I haven't yet found a great way to search through these results, but there should be some gems in there!"Fun facts" are, sadly, often less than fun. But here's a genuinely fun fact: most books published in the US before 1964 are in the public domain! Back then, you had to send in a form to get a second 28-year copyright term, and most people didn't bother.
Cheers,
A. W.