There are super markets in all places. To buy food for several days the best place is Manacor:
Mercadona at the Plaza Ramon Llull offers everything you may need. From here it is a short distance to walk to downtown Manacor (restaurants, cafés and shops). There is a second, more remote Mercadona which is not recomendable due to circumstancious parking.
Hiper Centro, entering Manacor coming from Palma on the left hand side. A large supermarket that has everything.
Next to Hiper Centro is Müller, a german store for hardware and food, and vis-à-vis is Aldi, another supermarket and Rossmann (also hardware and food).
In Agromart, next to Aldi at the main road, you buy mallorquinean groceries. Recommendable!
And now quickly some breakfast buns: