I first heard this story in 2017. Having studied Shakespeare's Richard II for 'O' Level, I have retained an interest in this particular ruler; so naturally I was curious.
I could find no mention of Richard II's jawbone on Wikipedia, so I turned to Google for a wider search.
Google Books was quite helpful. Nigel Saul, in Richard II (1997) wrote: "On numerous occasions over the centuries [Richard II's] bones were disturbed by hands being inserted through openings made in the panelling on the sides. In 1766, according to Gerrard Andrewes, later dean of Canterbury, a Westminster schoolboy helped himself to Richard's lower jawbone. In 1871, when the tomb was opened and an inspection carried out, the remains, though well preserved, were in disarray. Anne's skeleton [Richard's queen, Anne of Bohemia] was nearly gone. Richard's was fairly complete, except for the lower jaw, scapula and some ribs, but throughout the tomb there was evidence of disturbance ... "
In Westminster Abbey (2004), Richard Jenkyns wrote that although Sir Christopher Wren was commissioned to carry out a restoration of the Abbey's exterior, "the interior, or at least its eastern part, was virtually abandoned to indifference and petty vandalism ... Schoolboys fought over Richard II's jawbone, until one of them stole it."
This is from Stephen Smith's Underground London (2004): "In 1776, an enterprising if morbid pupil of Westminster School managed to remove the king's jawbone through a hole in the tomb. A bone said to have held the royal lower set was sheepishly returned two centuries later."
On a website entitled Papers Past, I found this report from the Wanganui Chronicle of 1916, which quotes something called the Church Family Newspaper: "Ninety years ago, a boy at Westminster School, which adjoins the Abbey, burrowed through the sandstone foundation of one of the walls. Inside the cavity he found a skeleton, from which he succeeded in removing what turned out to be a human jawbone. He took it home to his father, who formed the opinion that his son had raided the tomb of Richard II.
"The bone remained in the family labelled 'Jawbone of Richard II,' until late in King Edward's reign, when the then owner sent it to teh (sic) King with an explanatory letter. After many formalities Richard's tomb was opened and, sure enough, the jawbone of the skeleton was found to be missing. It was replaced, and a parchment manuscript recording the circumstances was deposited in the tomb."
(Wanganui is a city on the west coast of the North Island of New Zealand. As to what its Chronicle was doing reporting on such matters as these, your guess is as good as mine.)
Finally (back on Google Books), in Russell Ash's Top Ten for Men – in a section headed "10 Preserved British Bodies and Body Parts" – I found this: No. 8 – King Richard II's jawbone. Richard died in 1400 and was buried at Westminster Abbey. In 1776 his jawbone was stolen by a schoolboy – whose descendants returned it in 1906.
The other nine body parts (I knew you'd want to know) are: 1. Jeremy Bentham's body and head; 2. Charles I's vertebra; 3. Oliver Cromwell's head; 4. George Cudmore's skin; 5. King John's teeth; 6. Ben Jonson's heel bone; 7. Sir Walter Raleigh's head; 9. The Duke of Suffolk's head; 10. The Earl of Uxbridge's leg
© Haydn Thompson 2017