Here's a reliable way to rip straight edges onto ragged-edge boards.
straight edge cutting jig

Attempting to rip a straight edge along a board with irregular edges can be dangerous or downright impossible. One solution is to tack a straight board to the irregular board with finishing nails. But unfortunately, this method leaves small nail marks in the top surface of the workpiece.

So try this method: Construct a carrier board from 34 " plywood to a width and length to accommodate most of your boards (14"x7' works fine in most cases). As shown, you can quickly clamp the workpiece to this carrier board, and then rip one edge. Remove the workpiece from the carrier board, place the jig aside, and position the just-ripped edge along the fence to straighten the other edge.