First, what causes this? Well, the best time to pick greens is first thing in the morning. We pick them, rinse off the chunks of mud, sort them into shares, and bag them. As soon as we get back to the fridge, in they go. But there they sit until it's time for shares and some of them have a tendency to wilt more than others.
What can you do? First, be as early in picking up your shares as you can. We put everything in coolers, but (especially as it gets hotter), that's no match for a refrigerator. Second, pop them into the fridge right away. Better still, stick them in a bowl of cool water in the fridge. It's amazing what a bit of cool water will do for slightly wilted greens.
Unless you're eating the greens raw, a little wilt won't hurt a thing. Believe me, there's nothing like hot steam or boiling water to wilt some kale. So just wash them off, trim them to fit your pot, and cook away. You'll never know they started out wilted when you put them on your plate (I like mine with plenty of butter, Glenn doesn't).