Personalized Shamrock Music Notes Light Greens T-Shirt. A shamrock comprised of green and yellow music notes is a fun design for family and friends during the March holiday of St. Patrick's Day and Celtic festivals. 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.