Stores typically sell dressed lumber. Here is a secret however there are times where it would be better to have wood that is 7/8″ thick rather than the typical 5/8 to 3/4″.
How on earth do you make the wood true? Often there is nearly an inch of crown to take out.
Merv showed me a trick the other week. I was recladding a staircase with oak so I bought enough rough cut lumber from him to do the job. I had always made a cradle and tacked the piece of wood to that and ran it through the tablesaw… which is tedius and takes 2 people.
He said take the factory edge off a piece of plywood and tack that to the board… then run that through the saw with the plywood against the fence. The pieces were only a few feet long, so it was easy to do with only 1 pair of hands.
What a great method… and just 2 little nail holes to fill later!
BTW, Merv sells dried cabinet grade lumber from the store for reasonable rates. You may have to give him a couple of weeks notice though, he starts getting pretty busy this time of year.