Here are two stories that might have inspired the songwriters:

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Miracle of the Wheat

In the time of St. Nicholas, people prospered or failed with the bounty of their wheat crops. Before they could fill their own storehouses at harvest, though, they had to deliver a portion to the emperor in taxes. When there was a drought or some disease in the fields, the emperor still got his portion first. Many people starved under this injustice, just as they do today in the poorest parts of the world.

Once when famine fell over the land of Lycea, Archbishop Nicholas learned that a fleet of ships loaded with wheat had arrived at the docks in Myra. He went and begged the mariners to feed his people. Fearing severe punishment for arriving at the emperor's docks without their full cargo, the mariners refused the request.

The holy bishop then promised them a miracle. If they would feed his people, he said, he promised them their holds would be full when the fleet arrived across the Mediterranean at Alexandria. Sure enough, this came to pass, and the mariners praised God for the miracle.

Nicholas, for his part, distributed the wheat to every family in need. There was so much that it supplied the men, women and children for two years, with enough left over to sow a new crop!

There's another "Miracle of the Wheat" legend illustrated here:

The apocryphal legend recounts that after the Holy Family passed a worker sowing wheat in the fields as they fled to Egypt, the wheat miraculously grew to full term overnight. A short time later, when the pursuing soldiers asked the farmer if he had seen the Holy Family, he replied that they had passed by when he was sowing. The soldiers incorrectly assumed that the Holy Family had passed by months before and so gave up their search.