Most cooks--even unadventurous ones--can easily identify the yellowish-brown crescents known as fennel seeds. That's because these tiny seeds, which actually represent the dried ripe fruits of the aromatic fennel plant (Foeniculum vulgare), have been handed down through the ages as a spice and food preservative. Their heady and memorable flavor, reminiscent of licorice and anise, is familiar to most people because fennel seeds are routinely used in rye bread. In addition to keeping fennel as a kitchen staple, people in China, Europe, and other parts of the world continue to use fennel seeds in teas, tinctures, and compresses to relieve myriad ailments, including stomach upset, gas, and coughs. Scientists have even looked into fennel's value as a source for synthetic estrogen. And even though evidence to support these and other uses is spotty, it's clear that fennel seeds do work for certain conditions. For example, chewing on a few seeds clearly helps vanquish bad breath. (Try them after meals or as needed.) Specially made fennel-flavored syrups appear to help ease coughs, and are widely used for this purpose in Europe. And stomach upset may well find relief with a gentle fennel tea made by simmering 1 to 2 teaspoons of bruised seeds in 8 ounces of water.