Warren,
You might try mixing oyster mushroom spawn with leaves shredded as finely as possible. Maybe add some soil,
compost or manure, both to add some nitrogen and to add bulk & moisture retention.
My parents have an ever growing leaf pile. I gave them some wine cap spawn I had left over. They mixed the spawn in the center and just let it be. The center of the pile is cratered now.
Might give it a try,
Eric