Metamorphoses Book 5: Triptolemus
A third muse sang of Triptolemus, Ceres' helper. She sent him to spread seeds around the land and to share the gift of cultivation. When he stopped in Scythia, the king, Lyncus, offered him a place to stay. During the night, the king tried to kill Triptolemus so that he could take credit for cultivation himself. Before he could harm her helper, Ceres turned the king into a lynx.
When the story ended, the nymphs declared the Muses the winners of the talent contest. The Pierids were still unsatisfied and they were hurling insults when the Muses changed them to magpies to punish their insurrection.