Cook the sausage about 8-10 minutes, until no longer pink, breaking it apart as you cook. Set aside.
Add the oil and onions to the pan and saute until tender, about 10 minutes.
Add the mushrooms, garlic, sage, poultry seasoning and pepper and saute until mushrooms are tender, about 10-12 minutes.
Break the eggs in a separate little bowl and beat.
In a large bowl, mix the veggies, sausage, and bread in a large bowl and mix in the stock and beaten eggs until all of the bread is moist.
Pour the mixture into a greased baking dish and cover with foil.
Bake for 20 minutes the remove the foil and continue cooking until the top turns golden brown, about 10 minutes.