"In the largest metropolis of what would become the United States, some residents occasionally consumed a “black drink” that was six times stronger than coffee — which could produce rather intense effects".
"A team of researchers from Illinois, New Mexico, Mississippi, and Pennsylvania has found traces of the rich beverage in pottery beakers excavated from the site of Cahokia, a once-thriving settlement near the confluence of the Missouri and Mississippi Rivers".
knife sharpening with a coffee mug ( How to / tutorial )
As with any ceramic you should apply water to the area of the cup your using to sharpen with it removes particles the knife leaves and will give a better edge .