Very old? Art pottery?

I was wondering if someone could point me in the right general direction on this. I’m not sure if it simply handmade (vintage) or truly old.

What do you think?

Purchased in the US at an estate sale (though they certainly had old British items too).

 

Tin glazed earthenware mug. Could well be 19th or earlier.

 

Is that clay buffy-white-yellowish or red? It looks redware in two pictures and a pale buff color in the pic of the entire bottom.

If it is red clay my first guess would be early Bybee pottery or some other Southern potter.

 

It’s definitely not red. Maybe this picture gives a better idea of it’s color.

 

It looks like there's remnant of an unreadable red ink rubber stamped mark on the bottom. Isn't that the way it always goes!

 

Yes, I couldn’t read it, sadly. I didn’t know if it being stamped (vs an imprint) gave any clue as to age or location it was made.

This was the best I could do (and it’s not helpful):