...וַיֹּאמֶר יְהוָֹה אֶל־מֹשֶׁה פְּסָל־לְךָ שְׁנֵֽי־לֻחֹת אֲבָנִים כָּרִֽאשֹׁנִ
Shavuot is also called Zeman Matan Toratenu--the season of the giving of our Torah--because during Shavuot we remember when we stood at Sinai and accepted the revelation of Torah. The metaphor of first fruits works here, too, because the revelation of Torah at Sinai is the first fruit of our redemption from slavery by G-d's "strong hand and mighty arm" celebrated at Pesach.
Once, when G-d wanted to give the Torah to humanity, G-d went first to the Egyptians and said: "Do you want my Torah?" And the Egyptians said, "Well, what's in it?" And G-d said, "It says 'You shall have no other gods before me.' " And the Egyptians said; "Well, we have a lot of other gods, so we don't want your Torah." Then G-d went to the Caananites and said, "Do you want my Torah?" And the Caananites, too, asked, "Well, what's in it?" And G-d said, "Well, it does say that