+1 with Cabinetman on using some other straight piece as a guide for the table saw.
If you do not want to attach with finish nails, use double sided tape. I have the wood turners double sided tape. This hold very well.
These days I will also attempt to straighten one edge of a rough lumber piece with my #5 jack plane. I can get close enough so this edge is used against the fence. Straighten the other edge then flip to finish the first edge.
Using a hand plane needs the board to be clamped with the edge up. May not be so easy for you.