
Theoretically, I could (It was put in the armies food suply to stop them from getting boners for petes sake!) because it is non-toxic. I wouldn't do it with the stump out though! KNO3 is not a dangerous chemical at all.
IT IS IN TOOTHPASTES FOR SENSITIVE TEETH AND IS A FOOD PRESERVATIVE! Hell, you can get it from manure and rotting organic material. Show your mom this and tell her that it's really not dangerous.
http://en.wikipedia.org/wiki/Potassium_nitrate