Everything tolerant non-toxic ground cover

Evening all.

The lad has asked if I will add to his willow tunnel network to feature a tunnel that you have to climb through. That means I'll need to make a mound of earth to climb over, whereas the rest of the network is on flat ground. It means that I'll need something to bind the ground up, so it doesn't just pull away when you climb it. Grass would be the obvious choice if it got enough light, but it wont, it will be in a willow tunnel, so permanent dappled shade punctuated with spells of full shade.

So I need a ground cover other than grass, that is equally non-toxic (in the sense that no skin rashes will happen, and there'll be no accidental poisoning from handling food without having washed hands after playing), that will take shade, and probably need to tolerate dry soil because it will be inside the willow tunnel.

Any ideas?

 

How about some heavy duty plastic mesh. Like they put on sand dune type beaches to stop erosion?
Jenny

 

How long is this tunnel network.

 

The bit that I'd need to bind up will only be about 5ft, as in about 2ft slope either side at about 45 degree angle, and 1ft of flat on top. The mesh idea might be the best option, I hadn't thought of that. Cheers.