How did the romans worship the goddess Ceres?

Ceres cult took many forms. She was the central deity in Rome's so-called plebeian or Aventine Triad (Ceres, Liber and Libera) , and was paired with her daughter Proserpina in what Romans described as "the Greek rites of Ceres". She played an essential role in Roman marriage and in funeral rites.

Her seven-day April festival of Cerealia included the popular Ludi Ceriales (Ceres' games). She was honored in the May lustration of fields at the Ambarvalia festival, and at harvest-time. She is the only one of Rome's many agricultural deities to be listed among the Di Consentes (six gods and six goddesses);

Juno, Vesta, Minerva, Ceres, Diana, Venus

Mars, Mercury, Jupiter, Neptune, Vulcan, Apollo

Rome's equivalent to the Twelve Olympians of Greek mythology.