Once upon a time, there was a young lad named Tom Tiver working on a farm. One warm July night, as he walked across a field, he heard a pitiful sobbing and wailing. Following the sound, he discovered it came from under a large, flat stone near a hedge. Moved by the cries, he lifted the stone.
Beneath it lay a tiny creature no bigger than a baby, with long, tangled yellow hair and a wrinkled, ancient face the color of fresh earth. It stopped crying and spoke to Tom in a soft, piping voice, calling him a good lad for freeing it. The creature introduced itself as Yallery Brown and offered Tom a reward: a wife, riches, or help with his work.
Tom, disliking work, chose help. Yallery Brown agreed but gave a stern warning: Tom must never thank him, or he would vanish. To summon him, Tom need only say, "Yallery Brown, come from the mools, I want thee!" With that, the creature blew a dandelion puff into Tom's face and disappeared.
The next day, and every day after, Tom's farm work was magically done for him. At first, this was wonderful. But soon, things turned sour. While Tom's tasks were completed, the work of the other farmhands was undone: their buckets were spilled, tools blunted, and horses dirtied. They saw strange things happening and began to shun Tom, blaming him for the mischief.
Tom found he could no longer do any work himself; tools would not stay in his hands. He grew isolated and was eventually fired. In a rage, Tom summoned Yallery Brown and shouted, "I'll thank thee to leave me alone!"
Upon hearing the forbidden word "thank," Yallery Brown let out a screeching laugh. He declared that since Tom had thanked him, he would never help him again nor would Tom see him. However, Yallery Brown explained he was now free because of Tom and would never leave him alone. He cursed Tom with a lifetime of misfortune, singing:
Work as thou will
Thou 'lt never do well;
Work as thou mayst
Thou 'lt never gain grist;
For harm and mischance and Yallery Brown
Thou 'st let out thyself from under the stone.
With a final sneering laugh, the creature floated away like a dandelion seed. The curse held true. For the rest of his life, nothing Tom did prospered; his children died, his crops failed, and his luck was always ill. He was forever haunted by the consequences of freeing Yallery Brown.