It’s not a seasonal poem to be sure, but here is an interesting essay on the earliest surviving secular song in English (via Daniel Gullo). Abstract:
Mirie it is while sumer ilast, dated to the first half of the 13th century, is the earliest surviving secular song in the English language, preserved only by the good luck of being written on a piece of paper kept with an unrelated book. We have the music and a single verse. This may be a fragment, but its wonderful melody and poignant lyric embody in microcosm the medieval struggle to get through the winter, nature’s most cruel and barren season.
This article examines the original manuscript, showing that the now-standard version of the song performed by early music revival players is not a true representation of the text. With a translation of the Middle English words into modern English, a short survey of the social background, a step by step reconstruction of the music, and a video with medieval harp accompaniment of the reconstructed song.