Pica
A craving for something not normally regarded as nutritive.
For example, dirt.
Pica is a classic clue to iron deficiency in children.
It also occurs in zinc deficiency.
Pica is also seen as a symptom in several neurobiological disorders, including autism and Tourette's syndrome, and is sometimes seen during pregnancy.
Pica is a Latin term for magpie, a bird that gleans all sorts of things for its nest.