Cut the mushroom stems off at the cap level. Place the heads in boiling salted water. Simmer till they sink to the bottom. Strain. Boil marinade water with peppercorns and bay leaves for 30 minutes. Add salt and sugar. Stir till dissolved. Add the vinegar, bring to a boil. Place the mushrooms in small jars. Cover with hot marinade. Close the jars. Keep refrigerated. Use for canapes and salads, or as appetizers. Yields 4 -20ºC luid pint jars.