In the magnets on the left, I used a photo of the Pacific Ocean that I took. In the ones on the right, I used a piece of scrapbooking paper I bought at a craft store.
I am putting them on little rectangles I cut out of white cardstock and into little zip-top bags. These will make great Christmas gifts!
P.S. You do want to use good, strong magnets for these because they are heavy. I found rare earth magnets on eBay fairly cheap.