Earth Mother

The Earth Mother's origin is unknown, but she is most likely simply created by one or more of the forces of magic that created most of what is Arcanalia and the creatures and plants that populate it.  
What is known about her is that she is a caring and nurturing spirit, who found the sad animated rock like creations that Flarg had made and sent out to bring him food:  The Orcs.  Chances are that these creatures would not have survived if left to Flarg.  While she could not remove them from him she used her magic to make them into better creatures who could succeed in this world.  The orcs thrived under her care.
While they still worship Flarg in fear, the Earth Mother they worship in reverance.