1923 S Buffalo Nickel

I don't see any signs of an S mintmark.

not seeing any sign of mintmark, but on the coin as a whole, I think it was buried possibly the source of the pitting all over, the coin has been through corrosion of some sort. It's a slightly better date (semi-key even) but really only a tough to find coin in really high uncirculated grades today. The price starts getting expensive in VF and above. This date/mint mark combination is known for a weaker strike, I've had quite a few I've bought hoping to get them into a TPG holder in Mint State, they've always come back AU55 or AU58, I think I got a single one into a NGC MS62 holder out of maybe 30 different coins, everyone I felt was borderline MS so the TPGs are tough on this date as well. I still have a bunch of lower grade examples myself just because it's one of my favorite date mint mark combinations. Your coin is very typical to many I have in lower grade, I see that corrosion or pitted look often.

Funny coincidence is I have 5 of the lower grade 1923-S Buffs sitting in front of me right now, I just pulled out of the safe. Here they are on my mousepad, with a 1925-S tossed in too. I was just getting ready to photograph them for sales.

I'm not so sure even of that.
Definitely no "S" mintmark (on the reverse, of course).
But it also looks like the date has been altered.

I think the date looks just fine. Compare to a few of the ones I have they are all 23-S though.

I see it but all that deterioration is also over it or like I said it could be messed with as far as the date it looks fine to me maybe struck through die cap?