mysophobia

n. - dread of dirt.

mysophilia

n. unnatural attraction to dirt.

Edit: Via Dr.Bill and a little research on my own:

" Pica: eating earth or clay or chalk; occurs in some primitive tribes or sometimes in cases of nutritional deficiency"

Dr. Bill mentioned the connection between pica and magpies.

Second edit: "Pica is a Latin term for magpie, a bird that gleans all sorts of things for its nest."