On the way to other things, I noticed one of Open Road Media's public domain editions is free right now: the short story,
The Vampyre, by John William Polidori. (Of course, there are also nice versions of this in MR's Patricia Clark Memorial Library, but if you want it natively in your Kindle or Kobo library, here's your chance for free.) And my experience of Open Road's public domain books is that they are generally pretty good, especially compared to what often ends up on Kindle or Kobo. So here are links...
Kindle US:
https://www.amazon.com/dp/B01N14SZSN
Kobo US:
https://www.kobo.com/us/en/ebook/the-vampyre-22
Oh, and there are a couple of non-fiction Open Road public domain titles free right now too - see
this post.