Historical clue formulations

• Machines on hay farms — 2020-02-18
• Haymakers? — 2015-05-03
• Farm machines — 2012-06-24
• Farm machines — 2011-07-12
• Some farm machinery — 2010-06-30
• Haymaking machines — 2006-03-08
• Some farm machinery — 2004-12-12
• Some field workers — 2001-07-08
• Plantation workers — 1999-09-26