The Monte Amiata area offers an extensive calendar of chestnut festivals. The oldest is the Crastatone filled with music and dancing in the streets, reliving the atmosphere of an authentic rural village. The festival takes place within the town’s medieval city walls, the Rocca Aldobrandesca, which encircle the old town centre. Food stalls are set up in the streets and alleyways, serving food made from chestnuts. More info (in Italian) here.
Vivo d’ Orcia celebrates the Mushrooms and the chestnut fest on the second and third weekends of October with a multitude of specialties made using local mushrooms. You can expect to see many food markets and mushrooms exhibitions at the festival.
Every year year, the medieval town of Abbadia San Salvatore hosts the Autumn festival: an entertaining exhibition of local artists and kiosks selling traditional local dishes. Here you can join guided walks in the woods looking for mushrooms and chestnuts. But there is much more, check out here all the info about the Autumn fairs in the Monte Amiata area www.amiatautunno.it