For my first class for a OBW, the teacher was kind enough to go with me to find a fabric. I remember the repeat needed was 24", make sure the fabric has a true repeat (I have a piece that doesn't and it gave me fits on another project), check that there are no flaws and you'll need gobs of it (was it four yards??). Too bad that online sellers don't include vital information in their descriptions, at least fabric.com has the ruler at the base of the sample and you can see the half drop repeat of the bird.