I just heard about this tradition on our National Public Radio station, so I decided to look into it.
Plough Monday marks the traditional start to the English agricultural year. It is the first Monday after the Epiphany (6 January) and the tradition dates back to the 15th century.
This is the information I found for the tradition from the Plough Monday website:
In medieval times the ploughboys were supposed to return to work on Plough Monday, the start of the new ploughing season. Instead the plough was paraded through the streets with the aim to extort money from the wealthy landowners.
The exploits of the farmworkers varied, largely depending upon the region of the country they hailed from. Generally, in Cambridgeshire and Norfolk the ploughboys performed a dance called molly dancing, in the North East they danced with swords and in the East Midlands they performed mummers plays. The penance for non-payment was to have the front doorstep pulled up with the plough. The itinerant plough boys, often known as Plough Jacks, Plough Bullocks or Plough Stots, depending on the locality of the custom, would blacken their faces as a disguise, a tradition still practiced today. In the Cambridgeshire Fens children would collect money, often before school, this was known as Ploughwitching. It is known that Plough Monday was recognised as early as the 1400s and at that time was often connected to raising parish funds through the church. Plough guilds often maintained plough lights in the church and money was raised to keep the plough light burning.