Both these books were written by Leo Brodie. My dad had them because he used Forth at work. I was only 6 years old when I read them back then, but I absolutely loved those books. They were what got me into programming and I still consider them among the best written programming literature ever. They're both available for free now:

https://www.forth.com/starting-forth/

http://thinking-forth.sourceforge.net/

Seconding "Starting Forth" and "Thinking Forth".

After that, Jonesforth (https://rwmj.wordpress.com/2010/08/07/jonesforth-git-reposit...) is an excellent example of Literal Programming that starts with an Assembly listing and bootstraps into a complete usable Forth system. No better way to learn Forth than to actually implement one...