Preheat oven to 350°F (175°C).

Drain the canned peas.

Chop the celery into small pieces.

Chop the bell pepper into small pieces.

Finely chop the onion.

Saute the onions, bell pepper, and celery in margarine until softened.

In a large bowl, combine the sauteed vegetables with the drained peas, mushroom stems, and mushroom soup.

Add a dash of cayenne pepper to the mixture.

Mix all ingredients thoroughly.

Transfer the mixture to a baking dish.

Top the casserole with bread crumbs.

Bake at 350°F (175°C) for 1 hour, or until golden brown and bubbly.