At our house, when we refer to "greens," we're not talking about lettuce (though many of the cooked greens we eat can also show up in a salad bowl when young and tender). More often, we're talking about cooking greens -- kale, collards, mature mustard greens, chard, brusselini... the list goes on).
We eat 1-2 pounds of greens at our house each week (sometimes more). We like to steam kale and add it to any number of dishes to boost nutritional content. We also like to saute greens and serve them as a side dish. We've gotten so used to the concept that we almost can't imagine an enchilada dinner that isn't served over the top of a healthy serving of sauteed kale and jalapeno peppers.
Basic Sauteed Garlicky Greens
Other recipes featuring greens:
Kickin' Greens & Garlic Pasta
Greek Pasta with Greens
Red Curry with Napa Cabbage & Carrots