One thing I learned the hard way about storing #2 pine... Clamp several of them together and store them that way. It does not need to be fancy, just clamp 3-5 boards, flat side facing each other, with a clamp on each end. #2 pine is only dried to about 20% (so it is easy to nudge one way or the other when building something). When it dries out it gets a lot harder to bend. And flat sawn lumber ALWAYS moves when it dries. So if you clamp them first, they will at least dry pretty straight.
(When I built Mrs Inor's She Shack, I bought a whole pallet just to have some extra on hand. The outer boards on the pile bent all to shit as they dried but the inner boards, with the additional weight on them, dried straight.)