I found this really old book from 1938 for learning German which is quite the artifact, one from 1944 on how to survive an atomic bomb which is also super old and has some funny advice/a picture on wearing a fedora to protect yourself from the heat flash... some book from 1924 on mathematics which takes a historical analysis approach to teaching called mathematics for the million which is pretty cool. It has a lot of 'field trip' kind of exercises which makes me feel like learning math was probably a hell of a lot more of a fun thing to people back in the day. a more modern book which is probably a lot better to be learning german from is in there, another one from 1950s with andy warhol illustrations for spanish learning called "madrigal's magic key to spanish" which i lend to friends when they come here to pick up some spanish fast I can highly recommend. I got a second copy after some absolute walnut took off on a plane with it and didn't even bother learning spanish, it's that good.
I also got a couple of computer books. Concurrency in Go (oreilly) and this one thicc as heck tome which is the textbook for the SEED security labs which is also super good, because it comes with a bunch of virtual machines. Really nice source for levelling up your understanding of application vulnerabilities in C (and by extension other languages, but I was really glad to find something with these fundamental examples) https://www.handsonsecurity.net/