No, they're not hallucinogenic! But they are delicious. About ten years ago, I did some informal English tutoring with Hermine, who was visiting from Austria. I helped with her English and she taught me some Austrian recipes. Here's one of them. It's still a favourite.
Button mushrooms (enough for two people), cleaned and sliced
1 small onion
2 tbsp sour cream
1 tbsp flour
pepper and salt
Dice the onion finely. Cook it with a little olive oil in a saucepan, till soft and golden. Add the mushrooms and cook until the juice runs from them. Combine the sour cream, flour and about half a cup of warm water in a separate bowl. Add this mixture to the mushrooms and onions, and cook, stirring often, until it all thickens. Add pepper and salt to taste, and a little chopped parsley near the end of cooking. Serve on toast or (as I did last night) with home made garlic bread. Yum.