A rip of plywood, some blocks and a table saw will help you repurpose cruddy lumber from the bone pile into backing
Framing lumber comes out of the factory bent because the factory is a forest. Cutting a straight line on a crooked board can be difficult and dangerous, so it is best to make a jig.
Find a scrap of sheet stock with a factory edge and rip it about 5 inches wide.
Fasten a backing block to the end, so you can screw a push board into it, forming the business end of the jig.
Spacer blocks are screwed into the straightedge at each end of the crooked wood.
A second block holds down the workpiece while you move it through the table saw.