Dill weed was a seasoning made from the ground leaves of an aromatic herb indigenous to the Eurasian region of planet Earth.
In 2284, James T. Kirk used dill weed to add flavor to Ktarian eggs, a favorite breakfast dish of Kirk's lover at the time, Antonia. Kirk was preparing the meal for Antonia in order to soften the blow of re-joining Starfleet.
In the Nexus, Kirk revisited the day he told Antonia he was leaving. When Jean-Luc Picard found him there, Kirk asked Picard to bring the dill weed to him. (Star Trek Generations)
In 2373, Neelix used a little dill weed to flavor scrambled Porakan eggs, along with a touch of rengazo. (VOY: "Flashback")