No pattern, per se. I used a small motif from an out-of-print cross-stitch book that I picked up last summer at the Five-Colleges Book Sale.
To make the bookmark less floppy (and hide the messy wrong side!), I added a felt back:
To do this, once I was all done with the colored design, I simply put both the felt fabric and Aida cloth onto my Q-snap frame and stitched the thin dark brown border through both pieces, to tack them both together.
Then I cut a rather generous border around and pulled away one row of the Aida cloth around to make a frilly edge. I imagine more will fall away over time, as it's used more. This was a good project to use some of the long, skinny strips of leftover Aida that I cut away from larger cross-stitch projects.