A urban legend in the making, eh? What puzzles me, is in order for this to even be true, a farmer was out planting in mud. Really? MUD?!!!
I'm no expert on planters, but I can see where they may not work too well in enough mud to cause one to get stuck. Wouldn't mud also clog the holes the seeds are supposed to come out of?
Until further research or testimony, I'll concur with Rupert on this.