There was much in the news at the end of 2017 about the first time since 1998 that US copyright protected works were going to start breing released into the public domain annually, starting with those from 1923 on Jan 1 2019. Here is a useful link about that and, most importantly, how to find those works for free online.
https://motherboard.vice.com/en_us/ar...
Also, this is a great resource for classic children's books to read free online:
https://mymodernmet.com/childrens-boo...