Good thinking with the OSB!
One of our neighbors recently got the free county mulch delivered to their driveway, but since the county just dumps whatever they have sometimes you can end up with 10 yards of mulch for a 2 yard job. The neighbor took what he needed and put a "free" sign on top of it. It took us quite a few trips back and forth with our little Highlander to get enough mulch for our backyard, but it was a big blessing to us too!
And as a bonus, it was heavily laced with pine needles: much appreciated by our overly-alkaline soil.
Nice! Free mulch is a blessing, and those county guys seem to dump on any sucker they can find!