I know what straight grain is, but can't help you with the French fold. I am curious, too. Straight grain means not on the bias, cut straight up and down, not 45 degree angle.
After reading craftybear's google, I am still confused about French fold. Is it when the binding is folded in half stitched on one side to the quilt, then folded over and (hand stitched) to the back of the quilt? It's never been called that before. Hmmm. Learn something every day.