Everything is grist for the preacher's mill. I [Adrian Rogers] cannot give you a specific source from where I get my general sermon material, for the source comes from life itself.
For years I preached an average of six sermons per week. It seems like all my waking hours I was watching, looking, listening, making notes, or gathering materials.
I set up expandable files in my office containing some idea or theme that has caught my interest, and I begin to drop materials into those files.
I may drop whole books in because there may be material in that book that I will refer to during preparation. I may drop newspaper clippings, cards, or other sermon notes into the files. Now whether or not that information will be applicable when I read it in detail, I know not, but at least it is there so I can review it. I gather this material from everywhere just by keeping my eyes and ears open.
*This question and answer were extracted from "Love Worth Finding: The Life of Adrian Rogers and His Philosophy of Preaching.”