I am not a fan of playing in dirt for several reasons. Parasites, Bugs, Animal Excrement. If you use dirt from your yard it will most likely contain either bugs or parasites. If you buy it in a bag, it will most likely contain manure or chemicals. Dirt is not my thing.
So I decided to go get some free dirt from Starbucks. They give out their used coffee grounds in huge bags for FREE! Best of all, it makes the BEST MUD!!!! It works out really well for mud pies, dirt play with toys like cars, animals, dinosaurs, etc.