You can make a kind of quince jelly/butter out of the fruits in the fall but you have to add a lot of sugar they are pretty tart. it ends up tasting kind of like cranberries or rhubarb. Not really sure it is worth the effort, but YMMV. The flowering quince fruits don't get as big as the true quince, and in my experience the resulting butter doesn't get that pink color true quince does.