Read here for more on phytonutrients: http://www.dana-farber.org/uploadedFiles/Library/health-library/nutrition/phytonutrient-rich-foods.pdf
To yield the most nutrition, thaw frozen foods rich in phytonutrients in the microwave. Pesticide-free vegetation not from a hothouse typically has more phytonutrients. Steaming usually retains or even improves the amount of phytonutrients. If boiling, try to drink the water-boil pasta or grains with it or use it for stock or soups.
Almonds
Granny Smith apples..and crab apples. Glad I ate a lot from our tree as a kid!
Avocados
Berries, especially chokeberries and blackberries
Wild and pick-your own blueberries
Purple carrots
Citrus, especially grapefruit
Flax
Black and red grapes
Garlic, chopped and set aside for 10 or more minutes before cooking
Greens, notably dandelion greens and arugula
Hazelnuts
Fresh herbs
Loose- leaf Lettuces with red and purple; bitter is better
Green onions aka spring onions and scallions-the green part is best
Green, black and white teas
Heirloom Tomatoes; cooked is best for lycopene
Walnuts