We keep a few. When we go out, I put frozen water bottles in the socks (one bottle per sock). That way as they thaw out in our backpack and condensation forms, the sock absorbs it and everything in our backpack doesn’t get wet.
I always save them, thinking that I will have a light bulb moment for use by the preschoolers. I realized that my students can use them to erase the chalkboards — sock on one hand and chalk in the other!