Margaret Stafford (c. 1511 – 25 May 1537) is the illegitimate daughter of Edward Stafford, 3rd Duke of Buckingham. He tried to marry her to Thomas Fitzgerald of Leixlip, but things seem to have gone awry with Buckingham's execution.
According to some sources, Margaret married William Cheney or Cheyne (c.1509-c.1534). She was later "bought" by and became the mistress of Sir John Bulmer of Wilton, Yorkshire (c.1490- 25 Aug 1537). Apparently, they had at least four children and may have married sometime between 1534 and 1536.
In any case, Margaret and Bulmer were agitators. On May 7th of 1536 they were indicted for treason, but later pardoned. Bulmer, however, went on to plan an Easter uprising in an attempt to revive the Pilgrimage of the Grace. It didn't work.
Margaret was arrested by April 8th 1537. And by the 21st she and Bulmer were in the Tower. Along with others, they were convicted May 16th.
Sentenced to die, Margaret was burned at Smithfield. Bulmer was hanged, drawn and quartered at Tyburn.