There are explicit references to payment being made to morris dancers for Whitsun & other holiday activities in the late 1400s. By Shakespeare's time it was already considered a somewhat quaint (and I don't mean in the Middle English sense!) custom...he has the Dauphin in "Henry V" note that the French should pay no more attention to the English king's preparations for war than they would to the English preparing for "a Whitsun morris dance". And of course there's the Shakespearean clown, Will Kempe, & his famous "Nine Daies Wonder", in which he danced all the way from London to Norwich (or was it the other way round...?), wearing his bells & garters, & accompanied by a fellow playing pipe & tabour.

D.