What exactly are Duda'im? Why did Reuven bring specifically them to his mother?
Rashi: 'Duda'im' are jasmin [which look pretty and have a fragrant aroma].
Rashbam: Figs, which have a pleasant aroma.
Ramban and Seforno: A 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.
See Ramban, who is skeptical about the opinion cited by the Ibn Ezra, that this herb is a Segulah (possesses mystical powers) for pregnancy.
Seforno: Like garlic, which Chazal encourage to eat on Friday night - and perhaps even more than garlic.
Ramban: Even though it was out of season, he found them by chance.
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 1 did not take wheat or barley, but from wild flowers that were Hefker.
Oznayim la'Torah: Although he was only six at the time, he had already been trained not to take anything that was not Hefker.