http://www.icanteachmychild.com/2012/01/digging-for-bugs-in-the-mud-aka-chocolate-scented-playdough/

Mud play dough recipe – I usually change it slightly by reducing the cocoa to half a cup and adding half a cup of ground coffee. Makes it look more grainy like mud and smells delicious! We have used it to find worms ( pieces of string) and plastic play bugs. We made beautiful flower gardens for Mothers Day by placing Mud play dough in egg cartons and arranging flowers and butterflies.