I got this old 1970's pattern at a thrift store several years ago, but it has served me well in making lots of awesome cowboy shirts. The most detailed one I made was for Alec's 30th birthday.
Alec is really into dragons, so I embroidered 4 different dragons on the front and back yokes. They're playing musical instruments that he plays. I made the dragons detailed so that they would stand out as black embroidered outlines.
Making a shirt in secret without that person's measurements is a challenge, it helps to have a friend who is a similar size. The only part that I got wrong was the collar size, Alec can't button the top button without it choking him.