I have found that pound for pound leaf mold is the greatest amendment to my soil type.
I grow massive amounts of comfrey, have endless supplies of cow, goat and
chicken manure; worm bins and so on all add up to great garden soil.
The massive piles of leaves I throw into a corner to rot down a year or two give me very deep, black, rich soil that makes my clay / hardpan into true garden soil.
There is nothing more simple than a rotted down pile of leaves and it seems to be what all of my
trees and plants want more than anything else.