Farmer Maggot is ok, I guess, for Hobbit decks. They are the only decks with threat low enough to make his ability ok, and he is a little overpriced. 3 isn't very cheap. I still include him, for hopes of Steward of Gondor and some songs being able to buy him. His MotK hero I do not think anyone should use, except for joke decks.
He is the original Pennywise, being called "Penny-wise" by Tom Bombadil in "The Adventures of Tom Bombadil"
Farmer Maggot has excellent synergy with Tom Cotton. You will most likely want to play Farmer Maggot when you have an engaged opponent. This means that Tom Cotton allows him to be played without a resource match. As a further bonus for Tom, the attack of Farmer Maggot will be increased as well. — Nystrum 35