Rashi on Deuteronomy 33:14/רש"י על דברים ל״ג:י״ד

1וממגד תבואת שמש AND BY THE PRECIOUS FRUITS BROUGHT FORTH BY THE SUN — for this land lay exposed to the sun and it therefore produced sweet fruit (Sifrei Devarim 353:3).

2גרש ירחים [AND BY] THE PRECIOUS THINGS PUT THINGS FORTH BY THE MOON — there are some fruits which the moon brings to maturity, these are cucumbers and melons (Sifrei Devarim 353:3). — Another explanation of גרש ירחים: this refers to fruits which the earth puts out and produces from month to month (cf. Onkelos).