Setting the record straight Vegetables have plenty of protein, and they're complete proteins as well.

This is one of my favorite websites on Protein. Michael Bluejay does an Excellent Job.

http://michaelbluejay.com/veg/protein.html

Here's a quote from this excellent link -

"There's a very easy way to see the completeness of plant proteins, that most nutrition writers haven't bothered to do: Look at what's actually in the food!  It's not like this is a secret; that data has been publicly available from the USDA for decades, and now the USDA's database is even online.^4.1  Below is what it looks like when you actually look up the numbers.

Vegetables are complete proteins
Amino acid >	Isoleu- cine	Leucine	Lysine	Phenylalaline +Tyrosine	Methionine	Threonine	Tryptophan	Valine	Histidine
Need
Brown Rice
Tomatoes
Potatoes
Green Peppers
Corn
Lettuce (iceberg)
Celery
Cucumbers
Oats
Carrots
Broccoli
Pinto Beans

Amino acid need from the World Health Organization⁴, food composition from the USDA nutrient database^4.1.
Analysis is for each individual food all supplying calorie needs (closest to the "low active" category for a 5'11" 181lb. 25BMI male, as per the FDA).³

So when we compare the actual requirements to what plant foods actually contain, we find that basic plant foods aren't incomplete at all.  They have every essential amino acid, in excess of what we need.  It might not surprise you that beans are a complete protein by themselves, but even carrots are a complete protein.  Tomatoes are a complete protein.  Celery is a complete protein.  Even iceberg lettuce is a complete protein.
(Those who would object that we can't eat enough lettuce to satisfy our protein needs are wildly missing the point.  The point of using a day's worth of calories for a single food is simply to show how the food measures up, not to suggest that anyone could or should eat only a single food.  These plant foods are complete no matter how much or how little of them you eat.  That is, if only 1% of your diet is lettuce, then lettuce supplies more than 1% of your protein and amino acid requirements.)
Interestingly, the amounts for "Need" in the table are twice what they were until recently. The original recommendations in the WHO's 1973 and 1985 reports were based on William Rose's pioneering work in the 1950's, and were considerably lower.⁶  Rose determined the levels needed by his subjects by intentionally feeding them diets with a synthetic mixture of declining levels of amino acids until they became deficient.  After finding the highest amount needed by any subject, he then doubled that figure to arrive at his recommendation.⁷  And the current WHO recommendations have doubled their earlier figures again.  And even with all these increases, individual plants still measure up as fully complete."  

 Source:  http://michaelbluejay.com/veg/protein.html