She was born in London, the daughter of a prosperous merchant named John Lambert and his wife Amy, daughter of a well-off grocer named Robert Marshall. She was christened 'Elizabeth' and took up the name 'Jane' later on, for unknown reasons.
Jane married before she was quite out of girlhood to a merchant named William Shore, who though young, handsome, and well-to-do, never really won her affections. It appears that he was impotent, for their marriage was eventually annulled on that ground in 1476.
She probably became mistress of the king in late 1475 or 1476. Edward did not discard her as he did many of his mistresses, and their relationship lasted until Edward's death in 1483. Afterwards she was mistress of the queen's oldest son Thomas Grey, 1st Marquess of Dorset, and of William Hastings, 1st Baron Hastings, who was convicted of treason and executed in the Tower of London on 18 June 1483. (The precise order of these relationships is not certain.)
Jane was required to do an open penance at Paul's Cross for her promiscuous behavior, though this may have been motivated by suspiscion she had harbored Dorset when he was a fugitive. She accordingly went in her kirtle through the streets one Sunday with a taper in her hand, attracting a lot of male attention all along the way.
While she was in prison for her misconduct, she so captivated the King's Solicitor, Thomas Lynom, that he actually entered into a contract of marriage with her. This we know from a letter of King Richard to his chancellor on the occasion, pardoning Jane so she could be released from prison (into her father's custody) but asking the chancellor to dissuade Lynom from the match, if possible. Nevertheless, they were married and had one daughter. Although Lynom lost his position as King's Solicitor when Henry VII defeated Richard III, he was able to stay as a mid-level bureaucrat in the new reign.