(The). May morning is so called at Holne, near Dartmoor, because on that day a ram is run down in the “Ploy Field.” It is roasted whole, with its skin and fur, close by a granite pillar. At mid-day a scramble takes place for a slice, which is supposed to bring luck to those who get it. Said to be a relic of Baal worship in England.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894