Sage goes nicely with mushrooms indeed, and also in omelettes. Nice sprinkled on baked vegetables, with roast meats and in stuffing for poultry, especially fatty poultry like duck or goose. There are a lot of recipes for Sage and Onion stuffing, basically finely chopped onion or leek, breadcrumbs, sage, maybe other herbs such as tarragon, thyme or oregano, and a bit of egg, milk or apple juice to bind it to a stuffing consistency. Good with pork, veal or poultry, and has long been popular for Christmas goose or turkey.
Sage leaves can be burned as incense, infused as a tea (good for colds and fevers, also as a gargle for sore throat or mouthwash for sensitive gums and bad breath). A decoction of sage makes a good antiseptic wash, also helps to cover up grey hair in dark-haired people, and as a hair conditioner, again for dark-hair. It's a good plant to grow for bees, they love the nectar in the flowers, and drinking sage tea is purported to keep the mind alert and the cerebral circulation in good shape, hence its reputation as a useful herb tea for old folk to drink.
Sage is the symbolic herb of wisdom, and back in the days before toothpaste and toothbrushes it was the herb for cleaning your teeth, either on its own or mixed with salt.