The button in the Tice book (CSN-272A1) is a 1-piece solid cast button (made of pewter or other "White-Metal"). Your button is a 2-piece brass button.
In the Albert book, one of the two US-Navy-emblem buttons he says is similar to Confederate manufacturing (NA-119) is also a 1-piece solid cast "White Metal" button. The other maybe-Confederate button (NA-118) has different eagle-wings from your button. The top of NA-118's wings are as round as the top of a number 9. On yours, the wing-tops are more pointed.
In my professional opinion as a dealer of pre-1900s American Military buttons for nearly 40 years, your button is simply a no-backmark US Navy button. That being said, I can tell you yours dates from sometime before 1943, when the US Navy changed the emblem to having the eagle's head look toward the left side of the button.
I posted this 2 years ago never got any response so I'm going to post again because I'm really not sure why there's no back mark only thing I can think of it's confederate on page 240 of warren k. Tices book there's the same button I have and it's confederate navy with no back mark so hopefully yall don't think I'm crazy thanks for looking ! Also it on page 102 of Alberts book.
