Personalized My First Rodeo Western Cowboy 1st First Birthday T-Shirt. Whether you're looking for a cute onesie, a cozy t-shirt, or a fun accessory, our My First Rodeo Western Cowboy 1st First Birthday collection has something for every little cowboy. Wardrobe essential for looking good, 24/7. 5.0 oz., pre-shrunk 100% cotton. Seamless 1x1 rib collar. Shoulder-to-shoulder taping. Double-needle stitched sleeves, bottom hem and front neck. Note: greys are a cotton/polyester blend.