When I get my stuff milled, I ask for 9 3/4" X 7/8" dry pine. By the time my boxes are cut and assembled (and dried out even more) it usually ends up right around 9 1/2", sometimes 9 5//8".
It's hard to judge the moisture in the wood, even if you bought kiln dried stuff, as soon as you put it out in the weather there would be some swelling.