Have you ever seen white-ish or yellow-ish lumps that look like they are embedded in the back of your throat? These are likely tonsil stones (also called tonsilloliths), which are hardened deposits of debris and bacteria buildup in the craggy crevices of the tonsils. Tonsil stones are fairly common, and often treatable at home. Causes of Tonsil Stones Tonsil stones form when bacteria and material like dead cells, food debris, mucus and saliva get trapped in the tonsil crypts