Nice find with the ROT button. ROT purchased two button types in the 14mm size, dragoon cuff button with a D on the star and infantry vest buttons with an I on the star. A book titled “Uniform Buttons of the Republic of Texas” by Bob Shelton & Al Luckenbach notes that excavated examples have been found with the designating letter no longer visible. It is noteworthy that the star on the Dragoon cuff button consistently measures 10mm from point to point in contrast to the nearly identical Infantry cuff which is 9mm. The ROT purchased 10,800 infantry vest buttons and only 2,520 dragoon cuff buttons. Albert’s button book reflects the rarity of the buttons with a RV 50 for the dragoon button and RV 35 for the infantry button. I agree with Va Dave that this button has an I, but measuring the star points can help provide conclusive info. Really nice button.