Tonsil stones can easily look like white spots on the tonsils. They form in small pocket-like structures in the tonsils called tonsillar crypts. The pockets collect bacteria, dead cells, food particles and mucus caused by post nasal drip. Because they're usually white, off-white, or yellow-white in color, people who have tonsil stones frequently complain of white spots on their tonsils, especially as the stones grow larger and protrude from the tonsils. Doctors estimate about six percent or more of the general population suffers from tonsil stones at some point.