Nuts, beans, or anything made with soy protein. Boca burgers are really tastey if you like or used to like hamburgers, you might like them. I am not a vegetarian, but I like some of the stuff they eat.

From http://www.happycow.net/vegetarian_protein.html

"Rich sources of non-animal protein include legumes, nuts, seeds, yeast, and freshwater algae. Although food yeasts ("nutritional yeast" and "brewer’s yeast") do not lend themselves to forming the center of one's diet, they are extremely nutritious additions to most menus (in soups, gravies, breads, casseroles, and dips). Most yeasts get about 50 percent of their calories from protein.

Here are some examples of vegetarian foods with high sources of plant protein:

PROTEIN IN LEGUMES: Garbanzo beans, Kidney beans, Lentils, Lima beans, Navy beans, Soybeans, Split peas

PROTEIN IN GRAINS: Barley, Brown rice, Buckwheat, Millet, Oatmeal, Rye, Wheat germ, Wheat, hard red, Wild rice

VEGETABLE PROTEIN: Artichokes, Beets, Broccoli, Brussels sprouts, Cabbage, Cauliflower, Cucumbers, Eggplant, Green peas, Green pepper, Kale, Lettuce, Mushrooms, Mustard green, Onions, Potatoes, Spinach, Tomatoes, Turnip greens, Watercress, Yams, Zucchini

PROTEIN IN FRUITS: Apple, Banana, Cantaloupe, Grape, Grapefruit, Honeydew melon, Orange, Papaya, Peach, Pear, Pineapple, Strawberry, Tangerine, Watermelon

PROTEIN IN NUTS AND SEEDS: Almonds, Cashews, Filberts, Hemp Seeds, Peanuts, Pumpkin seeds, Sesame seeds, Sunflower seeds, Walnuts (black)

One excellent ingredient to look for is hemp seed protein. Hemp seed is an nutritious dietary source of easily digestible gluten-free protein. It provides a well-balanced array of all the amino acids, including 34.6 grams of protein for each 100 grams. The fatty acid profile of the hemp seed is extremely beneficial, containing omega-6 and omega-3 fatty acids in a virtually ideal ratio. Other beneficial aspects of hemp seed include a strongly favorable unsaturated-to-saturated fat ratio; a high content of antioxidants; and a wide variety of vitamins and minerals.

Additionally, super green foods provide an excellent source of protein (70% in some cases)."

I take it you're not vegan, so I'm going to throw GREEK YOGURT out there :) Mixed with a little honey or some fruit, it's absolutely delicious! And 17g of protein per 130 calorie serving (the 2% kind). Try it!

Thanks everyone for the great information! 

The Protein Trio-Tofu, Tempeh, and Seitan (TVP, too!)

• Tofu is soybean curd. It is high in protein and extremely versatile, since it has little flavor and absorbs the taste of most foods it is cooked with. It has a spongy texture, and you can but two kinds: Silken and non-silken. Silken can be used in smoothies for extra protein, while the other version is more commonly used in stir-Fry's, bakes and dishes. Tofu is also a good source of calcium and iron, as well as many antioxidants.
• Tempehis made of fermented soybeans. It has a stronger flavor than tofu, and is less versatile because of it. Tempeh has a higher percentage of protein than tofu.
• Seitanis made of wheat gluten flour and can be made at home. I recommend it because Seitan, in stores, can be as high as 18.00 a pound! I have found that you can make it for much cheaper. Commonly known as 'wheat meat', seitan has a chewy, meat-like texture. Many people substitute it for meat and can't tell the difference.
• TVP (Textured Vegetable Protein) is made from dried, defatted, soybeans. It is commonly used as a substitute for ground meat in dishes. TVP has a chewy, meatlike texture.

 Legumes

• Peanuts have about seven grams of protein per ounce. They also have good amounts of healthy fats and are a healthful part of a balanced diet in moderation. (Same as nuts and seeds...)
• Soy is the only plant source of complete protein. Tempeh and tofu are made from soy, but so is soy ice cream, cheese, milk, sour cream, and yogurt.
• Beans- Garbanzo beans, Kidney beans, Lentils, Lima beans, Navy beans. All are good sources of protein, calcium, iron and antioxidents.

 Nuts and Seeds

• See above (Peanuts)

 Those are common ones. Whole-Grains and some vegetables are also good sources of protein.

quinoa is, if I recall correctly, the highest protein grain. I didn't see it specifically mentioned.