Oysters poached in white wine, then reheated in a mushroom sauce, or sauce poujette.
(Could be tinned oysters for these oyster patties.) Shrimps in white sauce into which the yolk of an egg has been stirred.
Creamed salted cod.
Leftovers from lobster or crab cooked in Court Bouillon.
Or the tails of fresh-water crayfish, reheated in a white sauce.
Filleted dab or sole fillets in butter, diced, when cold, then reheated in a white sauce which has been fortified with yolk of egg thinned down with lemon juice.