The collar of my husband's shirt was worn.
Before: front view with worn fabric where the collar folds down
Before: back view of the collar, worn at the fold
Before: closeup of the worn collar, from the front/inside
Before: closeup of worn collar, back/outside view
I turned the collar: now the worn part of the collar is not visible when the shirt is right side out with the collar folded and buttoned down.
After: viewed from the front, the worn fabric is now hidden under the fold of the collar.
After: neither is there any worn fabric visible from the back when the shirt is worn (as it usually is) with the collar folded down.
After: the magic of this type of "mend" is that it isn't really mending at all. As you can see when the collar is popped up, as it is in this picture, the collar is still worn. I didn't change that. All I did was to flip the collar around so that (when the it is folded and buttoned down, as it normally is) the worn part is invisible.
After: here's an inside view, with collar popped up. You can see that the unworn part of the collar is on the inside. That doesn't make sense until you realize that when someone is wearing the shirt, the collar will be folded and buttoned down so that the inside of the collar is what is actually visible on the outside of the shirt.