I don't even think that coin would straight grade so, in my opinion, it definitely isn't worth the costs of grading. The surface damage on the obverse is fairly noticeable. Even if it did grade, I wouldn't put that coin at anything higher than VF-30 (which isn't a high grade). It's definitely a nice piece to have in any collection so I would keep it if I were you but it just isn't a candidate for grading. I'm actually very fond of the morgan dollar series and I have a 1921-S similar to yours. However, I wouldn't pay more than $15 for your coin because of the poor condition. That's $2.24 above melt value. My strong advice is to not even think about sending coins for grading before you learn more about what would make a coin suitable. Otherwise, you'll lose a ton of money very quickly.
Thank you for the advise. That's why I ask first. I don't have experience in grading coins. I will continue to ask and I hope I may have one valuable.