Pica

The above photograph is the stomach contents of a psychiatric inpatient with pica.

The rare disoreder Pica is characterized by an appetite for substances largely non-nutritive, such as clay, chalk, dirt, or sand etc. Even nails as you can see or glass. Some doctors believe the culprit may be a mineral deficiency. But for more information just read :

http://en.wikipedia.org/wiki/Pica_%28disorder%29