What to drink
Wine will be quite everywhere a simple good wine, sometimes rather basic, but quite generally good.
A sagra is a feast in a village, with dishes from the traditional Tuscan cuisine which was a peasant one. Back in the old times, peasants used to drink their own produced wine, a popular one. So in a sagra you will not find the rush to the stellar bottles common to some high level restaurants. Neither a wide range of Tuscany's best wines, as in all Tuscan restaurants.
In a sagra menu, you'll find a choice of red or white wine, though some sagras offer only red wine, as it doesn’t make so much sense to drink white wine during a Tuscan traditional dinner. It will be a local wine, mostly, and maybe from an agricultural cooperative based not far from the village: in Tuscany there are many cooperatives of wine farmers, rather everywhere. And it is usually made with Sangiovese grape, this too according to the regional tradition. It is served in carafes of different capacities, one liter, half liter or even a quarter of liter, and at the cash desk you'll be asked which one you prefer.
In some sagras, you'll find also few bottles noted on the menu, for those who like the idea of having a higher level wine during the dinner. Bottled wine will be more expensive than the tap wine served in the carafe.