I was looking at my wheats recently and noticed I had two 1946 s with different mint marks. I did some research and think I have the inverted " S " . I think there are three types. Is this the inverted S ?
Unfortunately, this isn't it. There were three mintmarks used in 1946. This one is MMS-004. If this were the coveted inverted mintmark, the top curve of the S would extend beyond the bend of the lower curve.
The mint mark on your coin is correct. Check the following site: http://www.lincolncentresource.com/San_Fransisco_Mintmark_Styles.html