"Bugeilio'r Gwenith Gwyn" (English: Watching the White Wheat) is an 18th-century traditional Welshlove song.
It describes the tragic love affair between Wil Hopcyn and Ann Thomas (The Maid of Cefn Ydfa) from the village of Llangynwyd in Glamorganshire. Ann belonged to a wealthy farming family but Wil was only a farm labourer. Ann's mother rejected Wil and forced Ann into a marriage with Anthony Maddocks, the son of a local squire.
A few days before the marriage took place Wil left Llangynwyd. Months later Wil had a dream in which Ann's new husband had died, so he returned home. However, when he arrived he discovered that in fact it was Ann who was dying, from a broken heart. Ann died in his arms that day.
Maddocks inherited the Thomas' estate and soon re-married. Wil died in 1741, never having married. Both he and Ann are buried at Llangynwyd.