Saffron Botanical name crocus sativus, is the most expensive spice in the world. Derived from the dried stigmas of the purple saffron crocus, it takes anything from 70,000 to 250,000 flowers to make one pound of saffron. Moreover, the flowers have to be individually hand-picked in the autumn when fully open. Fortunately, only a little needs to be added to a dish to lend it color and aroma; too much makes the food bitter and possibilities that large quantities of it can be toxic
Records detailing the use of saffron go back to ancient Egypt and Rome where it was used as a dye, in perfumes, and as a drug, as well as for culinary purposes. It reached China in the 7th. century and spread through Europe in the Middle Ages. The town of Saffron Walden, where it was once grown commercially, takes its name from the plant. Now, however, most saffron is imported from Iran and Spain which is recognized as producing the best quality, but it can also be found in Egypt, Kashmir, Morocco and Turkey.
http://recipehut.homestead.com/ExpensiveSpices.html
Yep and it is easy to grow your own to cook with.Just buy saffron crocus bulbs and harvest the threads yourself.