Did you know that can you toss seven tonka beans into a river to make your wish come true? You can, but it's so much more fun to bake with them. Tonka beans are the seeds of Dipteryx odorata, a tree native to northern South America. The inch-long, black, wrinkly seed has a hard shell, but when grated on a Microplane, it smells sweetly like vanilla, for which it's sometimes used as a substitute, and almonds. (Tonkas also lend that sweet smell to perfume and pipe tobacco.) Though popular in other countries, in the United States tonka beans cannot be used in food, because they contain coumarin, an anticoagulant that can be toxic in large doses. If you have health challenges, please use caution; for most people, however, tonka beans used a pinch at a time present no danger, and enhance the flavor of baked goods with a slightly exotic flavor. Some cooks suggest substituting mahlab, or a mix of vanilla and almond extracts, if you find yourself tonka-free.