Time to get out the garden hose and create some mud for your children to play in! As play expert Allison Gopnik says, "What all kids need is more mud, relatives and livestock!" So if you can find a dog or pig to wallow with...even better!
You can find ideas on how to make your own backyard mud kitchen you can find ideas at Community Playthings and 1001 Gardens.
Then, check out these books about sloshing about in the dirt and mud for inspiration: