Genesis 30:14-16

14Now at the time of wheat harvest Reuben [the eldest child] went and found some mandrakes in the field, and brought them to his mother Leah. Then Rachel said to Leah, “Please give me some of your son’s mandrakes.”

15But Leah answered, “Is it a small thing that you have taken my husband? Would you take away my son’s mandrakes also?” So Rachel said, “Jacob shall sleep with you tonight in exchange for your son’s mandrakes.”

16When Jacob came in from the field in the evening, Leah went out to meet him and said, “You must sleep with me [tonight], for I have in fact hired you with my son’s mandrakes.” So he slept with her that night.