Our county hosts a site where they shred and pile up mulch for any county resident to haul away. I have frequently partaken of this mulch pile over the years, and feel that my soils have benefited from the organic matter. I am curious to note that altho the landfill mulch piles themselves don't seem to have this, if I don't get it spread instantly after I bring it home, the mulch seems to go gray inside my pile, and I wonder if that isn't some toxic organisms that will cause troubles in my planting areas. So far, I really haven't noticed any specific disease problems. but this year I noticed the mulch I had stored in a trash can had this gray look, and it made me wonder. Is it still so fresh that it is slowing turning to ash? Or is it fungus?