When did they stop eating the Manna?
Forty days after Moshe's death (R. Yehoshua in Mechilta, Targum Yonasan. Refer also to 16:36:2:1. (In Devarim (34:6), Targum Yonason said that they ate 37 days after his death - 22 in Adar, and 15 in Nisan. Presumably, the contradiction is due to Midrashim that translators added, and became incorporated into the Targum (refer to Bereishis 38:25:5:1**). R. Yehoshua and Targum Yonason here must hold that Adar had 30 days, and they count the day of his death, and also Nisan 16, for they ate on the night of the 16th. - PF)
What is the Torah referring to when it writes that they ate the Manna until they came to inhabited country?
Rashi: It means that the Manna stopped falling when they were in the land of Sichon and Og on the banks of the River Yarden, when Moshe died. 1
Seforno: When the Pasuk says that the B'nei Yisrael ate the Manna for forty years, it means that they ate only the Manna and no other food. That lasted, the Pasuk is now telling us, until they arrived at inhabited country - the land of Sichon and Og, when they began to eat of the local bread as well. 2
How will we reconcile the phrase which states that they ate the Manna until they came to inhabited country (the land of Sichon and Og) with the previous statement that they ate the Manna for forty years until the fifteenth of Nisan?
Rashi: The former (with reference to after they crossed the Yarden) refers to when the Manna fell for the last time; the latter, to when they actually stopped eating it. 1
Seforno: The former refers to when they last ate only the Manna, the latter, to when they ate the Manna for the last time. 2
QUESTIONS ON RASHI
Rashi writes that they stopped eating the Manna on the 15th of Nisan. Bearing in mind that the Manna began to fall on the fifteenth of Iyar (one month after they left Egypt), how can the Torah state that they ate the Manna for forty years?
Rashi: This teaches us that the 'cakes' that they took out of Egypt (and which they ate from the fifteenth of Nisan until the fifteenth of Iyar) tasted like Manna.