Note this version doesn't contain the phrase "God speed the plough" but I think it is older than the versions that do.

From the Bodleian Ballads collection, Harding B 11(1150):


THE FARMER.

  Come each jolly fellow,
  That loves to be mellow,
Attend unto me and sit easy;
  For a bottle in quiet,
  My boys, let us try it,
For dull thinking will make a man crazy;
  Whilst here I am king,
  Let us laugh, dance, and sing;
Let no mortal appear as a stranger;
  But shew me the ass
  That refuses his glass,
And I'll order him grass in a manger.
    Lal de lal, &c.

  By reaping and mowing,
  By plowing and sowing,
Dull Nature supplies me with plenty;
  I've a plentiful board,
  And a cellar well stor'd,
And my garden supplies ev'ry dainty;
  I have land, I have bowers,
  I have fruits, I have flowers,
And I'm here as a Justice of quorum;
  In my cabin's far end
  I've a bed for a friend,
With a clean fire-side and a jorum.
    Lal de lal, &c.

  Was it not for my seeding
  You would have poor feeding,
For indeed you would soon starve without me;
  My mind is content
  When I pay my own rent,
And I'm happy when friends are about me.
  Draw near to my table,
  Ye boys that are able,
Let us hear no more words of complaining,
  For the ringing of glasses
  All music surpasses,
I long to see bottles a draining.
    Lal de lal, &c.

  Let the mighty and great
  Roll in splendor and state,
As I envy no mortal, I swear it;
  For I eat my own ham,
  My own chicken, and lamb,
And I shear my own sheep and I wear it;
  I have all things in season,
  Such as woodcock and pheasant,
And the lark is my morning alarmer,
  So may each good fellow
  When inclin'd to get mellow,
Drink the plough and the good honest farmer.
    Lal de lal, &c.