That is not a mint mark. Those are the engraver's initials: Adolf Weinman The mint mark for your coin, if it has one, would be on the reverse to the bottom left.
That's so cute.. As stated those are the designers initials. But it is understandable why you would think it is a mint mark with West Point Mint recently minting coins at their Mint for general circulation. Here is Mercury Dime Information https://en.m.wikipedia.org/wiki/Mercury_dime
Just as I posted this I found where someone said that the W is the designers initial and not a mint mark. This would make sense.
Believe it or not. It's not the first time someone has asked that question. It's a good question! That's how everyone learns
LOL. Welcome to the neighborhood @Rodney Cole. As a new collector, I can see why you might think the designers initials could be a mint mark, especially this one because of the wear. You can't really see the A, only a semi-flattened W. Buy a Red Book and it shows you where the MM are on the different demonizations, plus other good information. They are not expensive and even a used one has about the same information. Ignore the prices though. Good luck and have fun.
Read the first response as it states everything. Get and read the RS Yeoman Red Book. It will help you in more ways than I can state. Welcome to CT.