+1 for Bill's method.
Here in Texas I can get wildly priced wood that I'm not allowed to inspect that is claimed to be "best quality" but not guaranteed to be knotless ( or even close).
Less risk to just "find" the little that's good at a big box store. I usually get 2-3 boards from a new "rick" at HD, then wait for those to be sold to check again - usually withing 2-4 days.
But I am envious of those who have good suppliers and wish I could get consistent boards - from the same tree?