A few summers ago I was in Seattle and discovered these, pea greens. Aren't they crazy? I got these at the Atwater Village farmer's market. Take off all the tougher stems and saute them just a little bit, just enough to soften them. A little olive oil, butter, garlic, salt, and in this case fresh mint.
I cheated - I bought canned beans. Here's how hard this one is. Open a can of cannellini beans. Rinse them off. Dump them in a bowl. Add: dried red pepper flakes, lemon, garlic, olive oil, thyme. Or curry instead of the thyme. Or a million other things. Mash it up with a potato masher.
For the crostini I used a nice ciabatta bread. After they were toasted we rubbed them with fresh garlic and layered the beans-then-greens on top. But variations were adopted along the way.