I've used the outer leaves of lettuce heads for wrapping up tuna fish, hummus, or other squishy ingredients. I have used chard and collards before to wrap rice, split peas, or other legumes, or maybe scrambled eggs or falafel. Sometimes I will use them raw but if you wilt them or very lightly steam them, they are more flexible. Leafy greens are my favorite way to substitute bread. I love bread and will eat the whole loaf if I buy any, so bread is banned from my house.