Except soy, all vegetable proteins lack one or more essential amino acids and are called incomplete proteins. Your body pieces together the amino acids to form complete proteins, and so whether you consume all of your amino acids from one source or many types of foods doesn't affect your body's ability to build and use the proteins supplied by vegetable sources.
* Soy (Soybeans, Tempeh)
* Whole Grains
* Legumes (beans, peas and lentils)
(Info from livestrong.com)