These elegant wool socks are perfect for trail running. Not per se stretchy socks but they do a great job on your feet and are comfortable even when they get wet well. (We've had a lot of rain lately.) If you're thinking about getting ultra-lightweight Phd shoes instead, I have several pairs and I find they dangle a bit on my pinky toes (like many women, my big finger is a lot longer than my pinky) because they have absolutely no stretch and are cut very straight. A crumpled cloth can start to rub, especially if your feet get wet.