Leah’s son found something that Rachael wanted? Could you explain this?
"Now Reuben went in the days of wheat harvest and found 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." But she said to her, "Is it a small matter that you have taken away my husband? Would you take away my son's mandrakes also?" And Rachel said, "Therefore he will lie with you tonight for your son's mandrakes." When Jacob came out of the field in the evening, Leah went out to meet him and said, "You must come in to me, for I have surely hired you with my son's mandrakes." And he lay with her that night" (Genesis 30:14-16).
Jacob had ended up marrying two sisters, Leah and Rachel, even though it was Rachel whom he loved. This inequality in affection naturally led the sisters into rivalry over Jacob's attention. It didn't help matters that Rachel was barren and Leah was able to have children.
One day, Reuben, Jacob and Leah's first born son who by this time would be about 8 years old, found some mandrake plants growing in the field. Mandrake was an herb believed to be an aphrodisiac and to promote conception. It is also called a "love apple" or "may apple." Rachel sees Reuben carrying the the herb and wants them. Perhaps she thought they could help her overcome her barrenness. She asks Leah for the mandrakes, but Leah decides she wants something in return. By this time, Jacob has been spending more time in other beds than her own, so the bargain was that she would exchange the mandrakes for a night with Jacob.