Just another name for ravioli, really, although some are cut in circles. Mantua is known for squash or pumpkin-filled tortelli, tortelli di zucca.
Tortelli d'erba, or tortelli verdi from Emilia Romagna are filled with spinach or chard, and cheese, and served with melted butter and sage.
Tortelli piacentini are similar but shaped like bonbons, but they also make tortelli con la coda (or cun la cùa), that looks as if they are woven almost, with a tail on either end.
They take them seriously in Crema, as a dish for holidays and special events. There is an academy dedicated to the local tortelli cremaschi, stuffed with ground amaretti and mostaccini biscuits, raisins, candied citrus peel, Marsala wine, cheese, mint candy and lemon zest, and served with melted butter. Similar tortelli with sweet fillings (some fried) are made in many regions during carnival.
Images by ciao chow linda, Clop, Creative Commons License, terme sant'agnese