The background image is a photo of one of my numerous gaming book shelves. I don't own many pre-AD&D books, except as PDFs. The few books all the way to the left are the Holmes "blue book" and the Moldvay Basic Rulebook and Cook-Marsh Expert Rulebook.
I simply chose the shelf containing my "oldest D&D books" as a background. Perhaps I will create a more appropriate one if this blog ends up going anywhere. Stay tuned and see.