How can I cover mud in my shady yard if grass wont grow, but I still want my kids to be able to play there?

I am looking for the cheapest way to cover the ground that will last a long time and be practical for kids to play on. I am very handy and can install something myself. I have 2 plum trees that shed and can possibly ruin any surface that I put down.

How can I cover mud in my shady yard if grass wont grow, but I still want my kids to be able to play there?
Plant a shade loving grass like red fescue. You will need to know

if the plum trees have caused the soil to become acidic. If so, you will need to apply powdered dolomite lime first, several days

before seeding. Contact your local office of the CoOperative extension Service for more info.
Reply:sand box
Reply:i would first lay some sand down to mop up the mud. then some top soil and finally some grass seed for shady areas , once the grass grows you can use a leaf rake to drag the leaves off the grass leaving it nice and clean for the children
Reply:lay some turf. When I was digging my garden I removed the top layer (In squares) and put the turf where there was a lot of mud. Fixed it real easy.
Reply:have fun doing it, then.

:)
Reply:How about mulcing an area with real thick bark or cedar shavings? Maybe cut down some trees so the sun can reach the ground- then plant grass. There is a grass that will grow in shade but if it is too shady I'm not so sure. You might have to lose a few trees.
Reply:first suggestion paving