1) Used of trees or branches brought down by the wind, a valuable commodity.
The OED has evidence from 1464 but it is surely a much older term. In 1274, John de Miggeley was arrested in possession of ‘four cart loads of boards’ in Sowerby forest: they were from ‘a dead tree blown down by the wind’, but the charge was dropped when it became clear that ‘he had them … of the gift of Thomas le Ragged’, the chief forester. In 1300, Roger de Mowbray granted the forestership of Hovingham with the rights of windfall to Ralph Kirketon, suam forestarium … cum arboribus vento prostratis et ramis et tanno omnium arborum. More explicitly, the rights granted to George Buschell in Fyling included uprooted trees: 1518 omnia et singula lingna vento prostrata ad terram ac eradicata. Windfall had a clear market value: 1307-8 De ramillis quercuum, alnetis et de alio bosco prostrato per ventum apud Wygdon’ et venditis. Later references in English include: 1502 divers Fosters [foresters] use to carie on hors bak to Scarburgh suche wyndefallen wodde, Pickering
1549 ‘And to have, in the name of fuel … the wood fallen with wind called wind-falls’, Scagglethorpe
1622 every woodward maie take Blowen wood or Falne wood within his walkes, Pickering. Fallen trees were listed in the inventory of William Middleton’s assets: 1614 birkes fallen in the woode xxs, Stockeld. In Harrison’s survey of the manor of Sheffield is the following entry: 1637 For Windfall Wood & diging up of Old Roots for Charcoales Ł103 08s 00d.