Reine Claude - French Greengage Plum Jam
Two farmers grow the true European Greengage (Reine Claudes - French for "Queen Claude") and there's always a bit of a tiff as to who plucked them from the tree at the correct brix level (so the skins are not tannic).
Whenever they come into season, especially in Paris, there's an immediate frenzy making them almost impossible to nab. They are the traditional french plum used for jams, tarts, and eau de vie. Luckily, we know some kind farmers who give us the first pick of the finest plum variety.