Greetings Dennis,
Well, I strongly discourage this sort of landscaping around an established or newly planted tree. Honestly, I'm not sure how or why this concept ever started? Regardless, this sort of landscaping only serves to diminish adequate levels of oxygen from reaching tree roots (especially young or newly planted trees). Moreover, this sort of improper landscaping around the base of trees also increases soil moisture levels near the base of the tree which encourages premature butt rot.
If you are concerned with the landscaping around the base of your tree and your tree's overall health, I would strongly encourage you to contact your local University of Illinois Extension office or a local certified arborist for an on-site evaluation of your affected tree.
Best of luck!