This young woman was sent to the convent, even though it was the last place on earth she (or her sister, who accompanied her) wanted to be.
A philandering Carmelite friar from Florence deft with a paintbrush and quick with fresco technique, one Fra Filippo Lippi, was working in Prato at the time, and became enamored of her. Throwing vows of Bride of Christ to the wind, Lucrezia, then around 21, and the 50something friar began a heated love affair, which resulted in the birth of their son Filippino (Little Philip) in 1457.
Eight years later, a daughter, Alessandra, followed. Lucrezia and Alessandra, typical of life stories related to Renaissance women, fall off the radar; son/brother Filippino goes on to became a talented painter in his own right.
Some art historians maintain that the Feckless Friar painted his lady love many times, almost always standing in for the Virgin Mary. (They never married.)
Possible portraits of Lucrezia Buti:
Filippo Lippi, Madonna and Child, Uffizi
Filippo Lippi, Incoronation of the Virgin, Uffizi
Filippo Lippi, Madonna and Child with Stories from the Life of the Virgin, Galleria Palatina, Palazzo Pitti