FENNEL SEED. Although occasionally in some locations, you’ll be able to locate ground fennel seed, in most instances you’ll have to grind it yourself. Do this with a mortar and pestle. Or, place seeds in a plastic bag and pound with a hammer till pulverized. Remove from bag and roll with a rolling-pin, repeatedly, using hard pressure till powder-like. A coffee grinder also works well. Crush dried rosemary leaves the same way.