My mom and dad bought a set of world book encyclopedia for me when I was young. It was an extravagant expense for us. We got the least expensive of the three because, even then, they knew I would take care of them. I used to grab a volume and sit down and read it.
I think my parents got the World Book set when I was around 9. They had a really old encyclopedia (Source Book) that I loved because of the old pictures and articles. There was also a huge, also old, one volume encyclopedia that actually had things like a schematic of a 1930s vintage radio, etc.