Golf Digest. In the mid-80s, they had a recurring feature called The Tournament and TV Guide in every issue, which had small half-page blurbs about upcoming tournaments taking place that month, with partial graphic renderings of the courses they were played on and a complete scorecard (first it was just holes 14-18, then later 15-18).
During 1985, Golf Digest produced color foldout maps of the four major venues (Augusta, Oakland Hills, Royal St. Georges, and Cherry Hills) as well as the TPC of Sawgrass in the issues for the months that they were held in. I was fascinated by these, and tore them out, put them on my wall, and began drawing them. Then I began drawing my own. I was in the third grade.
I still have three of the five in a file folder (don't have Augusta or Cherry Hills anymore, which kills me because I live in Denver now), along with other maps from other GDs as well as Golf World and Golf Illustrated. I collected those for awhile.
I got the World Atlas of Golf (original edition) from my grandma soon after.... unfortunately, I wore out the cover and I have no idea where it is now.
Learning to play the game itself also had a tremendous effect. And that year, my home course changed the order of the holes, and I became curious as to why they did that. That kind of went on a tangent as to "who makes golf holes to begin with?"