It's typically 2" for depth and 3x3 yards (or 9.??? x 9.??? ft.) I get a 4 yards of mulch every year and this means I can cover a an area 15.5' X 15.5' to a depth of 2".
Thanks, I think that must be what it is (see my previous comment on 10 cubic yards). These measurements sound more in line with what he delivered. However, I think the price was excessive.