Reddit mentions of Bebop to the Boolean Boogie: An Unconventional Guide to Electronics

Bebop to Boolean Boogie is pretty good. Very easy and fun book to read. Covers a ton of great entry level topics.

https://www.amazon.com/Bebop-Boolean-Boogie-Unconventional-Electronics/dp/1856175073/ref=sr_1_1?keywords=bebop+to+boolean+boogie&qid=1573568129&sr=8-1

Then move towards something more FPGA specific like

https://www.amazon.com/FPGA-Prototyping-Verilog-Examples-Spartan-3/dp/0470185325/ref=sr_1_2?keywords=fpga+verilog+examples&qid=1573568177&sr=8-2

Knowing C will probably hurt you more than help you. Forget what you know about C when learning Verilog. You need to approach learning Verilog in a different manner. Verilog is not another top-down procedural language expressing instructions one after another. There are some general programming tenets that still hold true, and attention to detail in regards to syntax is important. But forget about line-by-line procedural execution because that's not how these hardware description languages work. You need to learn DIGITAL DESIGN before you learn Verilog....

EDIT: for clarity and to tighten up my thoughts.

What's your budget?
How old is your friend?
What equipment do they have already?

Regardless of age, I would recommend this book:
http://www.amazon.com/Bebop-Boolean-Boogie-Third-Unconventional/dp/1856175073/ref=sr_1_1?ie=UTF8&qid=1314736370&sr=8-1

Some other ideas:

• GC to sparkfun.com
  
• Subscription to Make magazine
  
• Some kind of Arduino
  
• Good multimeter, soldering iron, tweezers, magnifying glass
  
  
  

For what it's worth, the book that kickstarted my interest and understanding in digital electronics was a weird little book called Bebop to the Boolean Boogie. The one I read was the first edition; I stumbled on it randomly on a bookshelf (back when we had these things called bookstores; get off my lawn).

It managed to be a perfect mix of entertaining and informative, and helped the concepts sink in.

Read Bebop to the Boolean Boogie, it'll give you a basic run through of the hardware basis of modern day computing. It's a fun read too.

Check this out for a newbie friendly introduction to digital systems:
https://www.amazon.com/Bebop-Boolean-Boogie-Third-Unconventional/dp/1856175073/ref=sr_1_1?ie=UTF8&qid=1494656076&sr=8-1&keywords=bebop+to+the+boolean+boogie

Bebop to the Boolean Boogie. A very fun and informative read.