A few miles from where I live there is a small 'cottage-industry' type operation that grows gourmet mushrooms. Their growing medium is heat-sterilized sawdust packed in relatively small plastic bags. Size-wise they resemble presto-logs, but unlike presto-logs the sawdust is just hand packed in the bags, holes are punched in the bags and the mushrooms grow out through the holes. Twice a year they replace all the growing medium and the 'spent' medium is available, free for the asking, in large quantities. The soil on my property is quite sandy. Would this material be a good addition, dug into my gardening plots??
Note; This stuff is not mushroom 'manure' as I know it, with soil, fertilizer and other additions.