To ensure that the lasagna doesn't come out watery, it's important that the greens go in dry. Let all the water evaporate during cooking, and then blot the leaves with a paper towel if necessary after removing them from the saute pan.
Cannellini beans are full of fiber and protein. Collards, rich in vitamins A and K and calcium, are in the cancer-fighting cruciferous family. Parmesan rind -- don't toss it! -- lends an incredibly rich flavor. (No bacon required.)