This is a condition known as pica. It is very common in pregnancy but i've not heard of cravings after a miscarriage however.
"Pica is a medical disorder characterized by an appetite for substances largely non-nutritive (e.g., metal, clay, coal, sand, dirt, soil, feces, chalk, pens and pencils, paper, batteries, spoons, toothbrushes, soap, mucus, ash, gum, lip balm, etc.) or an abnormal appetite for food ingredients (e.g. flour, raw potato, raw rice, starch, ice cubes, salt)." - Wikipedia.
Pica can be due to specific deficiencies of minerals, in particular iron and zinc; malnutrition (inadequate or unbalanced diet, problems with digestion or absorption, certain medical conditions eg: celiac); obsessive compulsive disorder; mental retardation; and developmental disabilities. Pica is particularly seen in pregnant women, small children, and with developmental disabilities such as autism.
My grandmother actually suffered from pica for about 15 years before anyone figured out what was going on- she was anemic.
I suggest you talk to your dr about these cravings to make sure your not suffering from any deficiencies.
Sounds like Pica as the above posters suggested.