White mulch (undyed wood mulch which I think may be mostly oak) may be had for $24 for 3 yards at River Bend Sawmill on Cochran Mill Rd outside Leesburg. Google Maps is correct (don't bother looking for a web site). As of a few days ago, Cochran Mill Rd is closed between the sawmill and Sycolin Road due to reclaimed water pipeline construction to support Panda Stonewall.
Today I learned (from a friend, not the sheriff) that in Virginia, technically you don't have to tarp a load of mulch since it's "forest product", but I wanted to make it home with what I paid for, so we tarped it anyway.
Note to self: A 6x8 tarp is not sufficient to cover a load of loose material heaped up in the back of a full sized pickup. Stock up on 8x10s at HF.