fairy soup - happy hooligans - outdoor sensory activities for kids. This is also a free activity you could consider mentioning to parents; a trip to the local park and then play at home. Also called a messy mixture, or "perfume making"
Here& an arts and crafts activity for preschoolers and pre-kindergarteners: build brick buildings with homemade mud bricks made from dirt and water.
Mud Kitchen Food - Munchkins and Moms Make pretend food for your kid's mud kitchen using stones. Such a brilliantly simple idea to combine with mud pies!
Remarkable Preschool Math Center Ideas - How Wee Learn