Wash mushrooms and carefully remove the stems from the center of the caps. Place the caps into a suitable flat baking pan with hole from the stem up. Fry the bacon until it is crunchy. Chop the stems from the mushrooms very finely with a chopper. In a large bowl mix the chopped stems, half cup breadcrumbs, and fried bacon (including the bacon grease for flavor). Fill each cap until heaped with the stuffing mixture. Heat in microwave or oven until hot.