Why would a child enjoy eating dirt?

Pica: It is called pica. The ingestion of non-food substances can indicate certain nutritional deficiencies. You need to see a pediatrician.

Knowledge/craving??: Kids will eat a variety of things at least once, as their brain records the bland or bitter taste of a bug/leaf/ dust bunny/dirt as pleasent or not.Their voyage of discovery is a simple way to use taste to input data they desire but don't have. Beyond that, a kid may respond to cravings triggered by deficiencies by repeatedly ingesting dirt/paint chips etc. All kids who do this need an evaluation.

?: A few reasons, 1- a vitamin deficiency, 2- iron deficiency 3- or normal with some children just being kids.