I love mushroom anything and this is one of my favorite ways to prepare them. You can serve them as an appetizer or as a side dish. I threw a party once where I made a tray of these and one guy showed up early and ate the whole tray. I almost killed him. They are that good.
Clean some button mushrooms reserving the stems. Chop the stems along with some diced onion and celery. Saute this mixture in a pan until it softens and sprinkle with salt and pepper and some poultry seasoning to taste. Add some small cubes of bread and a bit of chicken broth and stir over low heat until you have a nice stuffing consistency. Let cool a bit and mix in 1 egg.
Place the cleaned mushrooms in an oiled pan.
Pack and mound the stuffing into each mushroom pressing gently to compact the stuffing.
Bake at 350 degrees for about 25 minutes. The top of the stuffing should be golden.