I had a fruitless mulberry in my backyard for over twenty years. It was old and big when I bought the property twenty years ago. It died last summer, leaving behind about a foot and a half (at least!) of leaf mould and pushed-up dirt. I want to plant other trees and plants in my backyard. I also have a garden plot where I'd like to dispense with some of the organic material it left behind, to level the yard.
However, I haven't been able to determine if the leaves, etc., are toxic or hostile to other plants. Nothing else grew under that tree. Nuthin'!
Is it advisable to use the built-up leaf mould as mulch in my vegetable garden?
If not, how can I amend the soil in my backyard to be more encouraging to new plantings?
Thanks for any assistance!

No problem using the leaf mold. Reason nothing was growing under the mulberry was the heavy shade.