Cinnamon is an expensive spice, which can be used for magical applications. To Winding Circle it comes with the eastern caravans. Dedicate Crane tried unsucessfully to grow the trees in his greenhouse.
Its magical properties include baffling tracker-mages. That's why cinnamon oil is often used by professional thieves. Aymery Glassfire uses cinnamon oil along with poppy to scout in Winding Circle for Enahar.