Without truffles, cooked asparagus tips, wild mushrooms sautéed in butter and garlic, smoked salmon, sturgeon or trout, or poached fava beans tossed in butter with fresh marjoram, will do. All mixed in at the last minute just before serving the eggs. Or use portabella mushroom caps - cook them in advance so the only cooking time is for the eggs.
Finely chopped (in good condition) scallion greens or chives sprinkled over the eggs brighten their look and taste.