Hi - sorry to butt in front of Shelley on this one, but I have had these tonsil stones before.
I had many many of them and the doctor I went to said that the tonsils have "cavities" in them and that when you eat, food particles get stuck in those cavities. After a while, bacteria mix with the food inside the tonsils and VOILA you get a stinky whitish tonsil stone. It eventually works itself out.
According to my doctor these are not harmful and just happen.
They are annoying however. The doctor was not aware of any way to rid yourself of these stones, short of removing the tonsils.
(I had mine removed because they were the size of plums! Not because of the stones.)
I would like to hear if Shelley has more information on these tonsil stones too.
Chairster