Plain store-bought mushrooms are generally safe. Wild mushrooms are the lethal risk — several species kill dogs. Never let dogs graze outdoors on mushrooms.
Store-bought only, plain. Treat any wild mushroom ingestion as an emergency.
Cultivated ≠ wild. Amanita and relatives are frequently fatal.
Vomiting, diarrhea, drooling, seizures, liver failure (delayed).
Wild mushroom ingestion = emergency vet visit, bring a sample/photo.