Reuben went and found mandrakes in the field and brought them to his mother Leah. — The Septuagint translated דוּדָאִים as μανδραγορῶν (mandragoron), which became Latinized as mandragoras, hence “mandrake.” As a plant, mandrakes are related to the potato family that spreads large spinach-shaped leaves in a rosette pattern. Its root resembles a human figure, and the ancient regarded it as an aphrodisiac and enhancer of fertility if used in small quantities. The Mandrake (Slandraffora officinalis) is of the family Solanaceae (to which the Potato belongs), and has a very peculiar appearance that grows in the early spring.
The ancients viewed mandrakes as “love-apples.” The Hebrew words for ‘beloved’ or ‘loved one’ דּוֹד (cf. Song 1:16) and for mandrake דּוּדַי (dûday) both share the same root. (Kimchi). Some scholars contend that mandrakes are uncommon in Mesopotamia, but they may have been present then. In any event, Rachel and Leah believed that the plant could medicinally assist their fertility. Ramban suggests that mandrakes might have been used to perfume her bed (see Prov. 7:17). It seems more likely Rachel and Leah believed in the magical properties of this plant and hoped it would help her get pregnant.
Mandrakes grow low, like lettuce, which its leaves resemble, except that they are dark green. Its dark-green, oblong, wrinkled leaves form a rosette. Its small plum-sized yellow-red fruits resembling tomatoes or small oranges have an unusual smell and taste (Song of Sol. 7:13) and may have been used medicinally as a narcotic or stimulant. Even in modern times, many third-world peoples still view the mandrake as having the ability to make an infertile woman fertile. 
Superstitions Regarding Mandrakes
The 18th-century biblical naturalist Tristram noted that the Mandrake has been the subject of many strange superstitions. Most of the Mediterranean world considered mandrakes as man-like plants, where some primitive societies believed that one could hear it scream when somebody pulled them from the earth. They observed that it resembled the shape of a man and that it shrieked and groaned when dug up; that the usual mode of procuring it was by tying a dog to the plant, whose struggles tore it up, but that the plant’s shrieks killed the dog! Sir James Frazier records a similar legend, “Man grows under the gallows tree from the bodily droppings of a hanged man. It is a plant with broad leaves and yellow fruit. But there is great danger in digging it up, for while it is being uprooted, it moans and shrieks so horribly that the digger dies on the spot.” 
Rachel said to Leah, “Please give me some of your son’s mandrakes.” — It is interesting to note this is the first recorded conversation having took place between the two sisters. Each possessed what the other had. Rachel was envious of her sister’s children, while Leah was desirous of Jacob’s love for Rachel. It would seem that neither woman communicated much with the other, much less commiserate over their mutual misery. Their bottled-up feelings now come out into the open, as each comes to see the face of the Other miserable and anguished. Each sister looked at the Other as though they were looking at a mirror.
Leah Confronts Rachel with a Personal Revelation
30:15. But she said to her, “Is it a small matter that you have taken away my husband?” — This is surprising disclosure is a sad commentary about Leah’s and Jacob’s marital life. As mentioned earlier, Leah’s recent infertility may have been more the result of neglect rather than nature. After the birth of her first four children, Leah thus became effectively ‘infertile.’ As G. Wenham observes, “Suspension of conjugal rights can, according to the usual interpretation of Exodus 21:10, be grounds for divorce.” Even if Jacob wasn’t contemplating divorce, from Leah’s point of view, she felt as if her husband emotionally divorced her. This would explain Leah’s explosive reaction when Rachel asked for her son’s mandrakes. She minces no words. There’s nothing polite about her demeanor, she wanted to be more than just a housekeeper, Leah wanted Jacob to value her as a wife.
Would you take away my son’s mandrakes also? — To increase his love for you at my emotional expense? Rachel has no answer to Leah’s sharp and disarming question, for she can now see perhaps the justice in Leah’s anguished complaint for the first time. Perhaps they remembered what their relationship was like before Jacob came to town. Maybe the bonds of sisterhood could still be salvaged. Rachel may have realized that despite their rivalry, her sister proved to be loyal and devoted to Jacob throughout their marriage. Despite it all, Leah was holding on to every bit of personal dignity she could muster.
Rachel said, “Then he may lie with you tonight for your son’s mandrakes.” — Rachel held to certain folk remedies rather than direct her attention in soulful communication with the Divine.
30:16. When Jacob came from the field in the evening, Leah went out to meet him, and said, “You must come in to me . . .” — Leah did not wait for Jacob to return to Rachel’s tent, for it would have been inappropriate for Leah to ask Jacob to leave Rachel’s tent to enter her own. It is also possible that Leah feared that Rachel might change her mind and possibly postpone it for another evening. Not wishing to take any chances of having Jacob reject her with another lame excuse, she forces Jacob to live up to his husbandly duties. The tender-eyed Leah behaved aggressively toward her mate. This may have been the first time Leah ever acted and spoke so boldly to her husband. Perhaps she felt she had little to lose. Jacob found this new assertive persona of Leah much more attractive. Leah became more extroverted, while Rachel became more introverted and reflective.
 Frazier continues: “In modern times the high value set on the mandrake as a potent charm, especially useful for its power of fertilizing barren women, has given rise to a trade in counterfeit mandrakes carved in human form out of bryony and other roots. The use of substitutes for the mandrake was all the more necessary in northern countries, because the plant grows wild only in lands about the Mediterranean, including Syria, Cilicia, Crete, Sicily, Spain, and North Africa” (p. 378.) Some places in Europe, witches were believed to use it in their potions to cure fertility (ibid., 384-485).
 James Frazier, Folklore in the OT, Vol. 2, 384-385.
 Kimchi’s Genesis Commentary.