I have a group of GFs (you gotta have good friends) and we all got into "rusting" fabric. That's where you take muslin and some old rusted metal, put them together and sit it out in the sun to set. We had Texas stars, chains, nails, horseshoes - all kinds of stuff. You can see my rusted fabric in the large rectangles in the outer border. I had also purchased some fabulous cowgirl prints from www.oldeamericaantiques.com and really wanted to use them in a project. When my friends saw what I had designed, they wanted to make one too. When you design stuff for other people all day, sometimes it's fun to just do something for yourself.
You can put a pieced picture in every block, but I chose to use the embroidery designs from our Rodeo Stars pattern, enlarge them, and stitch them in the blank blocks. I think it makes a really unique quilt and we all had a blast doing it.
One tip - the cowgirl prints were not washer safe so I dipped them in a color set solution before sewing them up. Let them dry and they're now completely colorfast.