Corn, though unusual To find in the old world, was brought back to Europe in the late 15th century, I believe.
When reading historical accounts, however, we must be careful not to confuse 'corn' with 'maize' (what we NOW call corn). In the past, 'corn' referred to livestock grain (oats, for example). Now, we use the word to exclusively refer to maize.

Here's some idle speculation for you: might carvings be added later to spruice up an otherwise drab space? Maybe the funding wasn't immediately available so the financiers planned for the future. Think about this. You purchase a nice home. A few years later, you add a deck and a hot tub.