Pam Bono has a pattern for a quilt with a Western saddle on it. Title is "Saddle's" #7769. Her web site is pambonodesigns.com. Now, if she rides strictly English, this may not be her "thing". I ride English and I am still making the Western Saddle quilt!
I have lots of horse (and chicken) related material that I have collected for my stash. The Alexander Henry Fabrics Collection "charras" has a nice Western panel. I have coordinating fabrics to quilt around the outside and border.I have other horse panels by Giordano Studios,LLC.. Wild Wings by Persis Clayton Weirs @ Springs creative Products Group, LLC has panels also. They have a lariet print Cp31611. This one matches the above panel of the Alexander Henry fabrics. I know horse shoe patterns, brands, spurs, etc exist. I have collected them all. These were fat quarters with no label on them. I look for a quilt block that have pieces that I can fussy cut the horses on. Have fun! Hope this helps!