What exactly are Duda'im? Why did Reuven bring specifically them to his mother?
Rashi: 'Duda'im' are jasmine [which look pretty and have a fragrant aroma].
Rashbam: Figs, which have a pleasant aroma.
Ramban and Seforno: An herb called 'Kanfasga,' 1 which has a pleasant aroma and promotes pregnancy. 2 Reuven brought them to his mother 3 when he saw that she was upset at the cessation of her ability to bear children.
Ha'amek Davar: Normally, minors bring Metzi'os to their fathers. Reuven was wise enough to know that this is proper for his mother, for an ornament. This is why "bi'Pelagos Reuven" (Shoftim 5:15) refers to astute minors (Gitin 89b).
See Ramban, who is skeptical about the opinion cited by the Ibn Ezra, that this herb is a Segulah (possesses mystical powers) for pregnancy.
Like garlic, which Chazal encourage to eat on Friday night - and perhaps even more than that (Seforno). Malbim - this is unlike human nature, not to want maternal siblings [who share his mother's attention]. Reuven wanted to help his mother; later, he perturbed Yaakov's bed for her honor (35:22).
Even though it was out of season, he found them by chance (Ramban).
What is the significance of the fact that Reuven found the Duda'im in a field?
Rashi: The Torah stresses it to point out that, in spite of the fact that it was the harvest season of the crops, Reuven (who was at most five years old - Seforno) did not take wheat or barley, but from wild flowers that were Hefker. Malbim - also, he did not take Duda'im of a garden, rather, from a field, where they are Hefker.
QUESTIONS ON RASHI
Rashi writes that it was the harvest season, so the Duda'im were Hefker. Why were they Hefker? They are worth more than ears of wheat! And what is the Chidush that he did not steal?
Ha'amek Davar: Even though they are valuable, at the time of harvest everyone is in the field, and the owner cannot guard them, therefore they are Hefker, like it says in Bava Metzia (21b). Rashi (Sanhedrin 99b) says that it was after the harvest, when everyone may enter others' fields. 1
Beraisa (Bava Metzia 21b): If one finds coins in any place where many people go, he may keep them, for the owner despairs. (The Gemara rejected that this is because people constantly check their wallets! Rashi explained why Reuven was allowed to go there. If the Duda'im are not normally Hefker, also after the harvest, why do people let anyone enter the fields then? - PF)