Some people say the good harvest is thanks to the large amount of equinox dragons bred in dragon parks that year and the many bumps on Nogard's newly hatched gourd dragon. The equinox theory one is surely wrong, but the gourd one may be true. The fact that Ro the Baker used a Cibumancy spell a few days before the harvest and he did not know what the effect really was may also be a reason. The harvest may be an effect of the spell.
The Om of Noms was celebrated with a lot of feasts with newly grown fruit and vegetables. This also led to the discovery of the feast dragon. In parks some wizards came up with the idea to hide Treat Baskets in parks for the park owners to find.