Every plant contains thousands of chemicals, most innocuous. Some of these chemicals are absolutely needed in the diet (vitamins), some have minor physiological effects before the body either converts them to energy or excretes them, all are toxic if taken in huge quantities. A diet that contains a wide variety of fruits and vegetables will most likely be healthy and contain all the chemicals that make it into the health portions of newscasts.
People tend to buy one or two types of fruits and vegetables and grow tired of them before they start to rot in the refrigerator or buy them and eat something else. I have to admit that, given a choice between a cupcake now or a sweet potato after ten minutes in a microwave, I'll usually take the cupcake. [Never take nutritional advice from someone who never eats junk. Don't date them, either - but that's another story.] A good way to get a good balance of fruits and vegetables and all the good stuff in them is to go by color. Here's a guide:
Purplish red (anthocyanins)
blackberry, blueberry, cherry, cranberry, eggplant, plum, prune, purple/red grapes, raspberry, red apple, red cabbage, red pear, red pepper, red wine, strawberry (and probably black beans, red beans and beets)
One anthocyanin is resveratrol. If you want that particular one of the thousands of anthocyanins, it's found in peanuts, red wine, grapes, blueberries, mulberries and especially in Japanese knotweed (which is poisonous and the most invasive plant known - it kills buckthorn!), which is where the supplements come from.
Another getting mention is quercetin. It's found in capers, lovage, apple, tea, onion, grape, citrus, tomato, broccoli, green leafy vegetables, cherry, raspberry, cranberry and prickly pear cactus.
Ellagic acid will probably be the next big fad. It's in raspberries, strawberries, walnuts, pomegranates and pecans.
Catechins, including gallic acid, are found in berries and green tea.
Pinkish red (lycopene)
tomato, guava, pink grapefruit, watermelon (and probably raspberry and red pepper)
Yellowish orange (beta-cryptoxanthin)
nectarines, orange, papaya, peach, pineapple, tangerine, yellow grapefruit
Yellowish green (lutein/zeaxanthin)
avocado, collards, mustard green, turnip green, corn, cucumber, green beans, green peas, green and yellow peppers, honeydew melon, kiwi, romaine/leaf lettuce, spinach, zucchini
Light green (flavonoids)
artichokes, asparagus, celery, chives, endive, leek
The term flavonoid is used in many ways; I'm using a very specific, restrictive one.
Bluish green (isothiocyanates [sulfurophane]/indoles)
broccoli, brussels sprouts, cabbage, cauliflower, bok choy, kale, swiss chard (horseradish, radish, mustard)
Deep orange (beta carotene)
acorn or winter squash, apricots, cantaloupe, carrot, mango, pumpkin, sweet potato, goji berry (turnip green, spinach, collards, cilantro, thyme)
There are hundreds of edible mushrooms and they contain thousands of phytochemicals. The best studied is from shiitake, but I recommend eating a variety of mushrooms.
Eat one from each group and you're up to the 9-11 fruits and vegetables commonly recommended per day (for 10 and 11, I'm counting anthocyanins and mushrooms twice). The very conservative USDA recommends 5-9 fruits and vegetables.
Other foods to consider:
Lignans: fatty fish, flaxseed, walnuts
Curcumin: turmeric, cumin
Pycnogenol: pine nuts
Caffeic Acid: honey
Phytic acid: sesame seed
When you get down to it, there's something good in almost everything. Eat a wide variety of foods. Fill your shopping basket with color.