The New York Times food blog has an interesting item titled "The 11 Best Foods You Aren't Eating". The foods they list are:

1. Beets
2. Cabbage
3. Swiss chard
4. Cinnamon
5. Pomegranate juice
6. Dried plums
7. Pumpkin seeds
8. Sardines
9. Turmeric
10. Frozen blueberries
11. Canned pumpkin

The idea behind the list is that many times, as was the case with the two books I recently read by Michael Pollan (The Omnivore's Dilemma and In Defense of Food) the easy critique of the "industrial" eating that contemporary Americans have taken on isn't joined to simple advise on how to direct your diet in a more healthful direction.
One of Pollan's points was that in the past culture helped pass on healthful diets (at least as an ideal...of course, in preindustrial societies, famine was a real possibility at times); and that "culture" in most cases meant "Mom". In contemporary society, mothers rarely have the leisure to cook properly, and so are not passing along much in the way of accumulated wisdom. Nor do children learn how to cook from their mothers, and so we need to reforge the broken chain of food culture.
So in the Times' list there are many foods that are healthful, easy to find; they should be items commonly found in most kitchens. We use all of these regularly in our kitchen, except for Pomegranate juice. Canned pumpkin is great, not only in pies, but in rolls. Prunes are great too--we've got a fabulous spice cake that uses stewed prunes in it. We've got Swiss Chard and Blueberries in the garden. And I've liked canned sardines ever since my father introduced me to them at the bar in the Old Colony Yacht Club when I was but a "wee lad". Cinnamon is used in so many recipes, Indian foods, chili, baked items, and mixed with sugar as a topping for French toast; turmeric is an essential in Indian recipes, and one in particular that we like is cauliflower.

Cauliflower, Indian-style

• One head of cauliflower, with greens removed and broken into small florets
  
• 1/2 stick (2 ounces) of butter
  
• 1 tsp. cumin seeds
  
• 1 Tbsp. Turmeric
  
• 1/2 tsp. salt

melt the butter in a heavy, large skillet or dutch oven under medium-high heat. Heat the cumin seeds in the butter, then add the turmeric and salt. Finally, add the cauliflower, stirring and turning so that it is covered in the butter and spices. Add 1/4 cup of water and cover for 3-4 minutes. Uncover, stir and serve.

Taking a second look at the list, I notice that all the items, except the Pomegranate juice, are among the less expensive items you might pick up on the grocery list, the vegetables especially when they're in season. Foods that pack a powerful nutritional wallop needn't be out of the reach of the poor. Among the "ethnic poor" I've visited over the years, there seems to be a storehouse of traditional recipes which are heavy on plant foods and rice, and which can be very healthful. But in the houses of the poor "natives", that culinary culture isn't usually in evidence, and the foods that they rely on are the kind that contribute to poor health. Because no matter what your culinary culture, you only buy what you can afford, and refined carbohydrates are cheap. In the past we've printed and distributed a brochure based on info from Bob Waldrop's "Better Times Cookbook" to help folks figure out a better way of buying food, but even that can't overcome the problem created by the gap in cultural food transmission that is evident.