How can we say that Shavuot is the day that we received the Torah if the Halacha is like Reb Yehudah who says that on the seventh of Sivan we received the Torah. Why do we celebrate on the sixth of Sivan?
The Magen Avraham answers that this is eluded to by the fact that the second day is also a Yom Tov. We call both the first day and second days Matan Torah.
The Chok Yaakov disagrees with the Magen Avraham. He says that this cannot be the answer because people in Eretz Yisrael don’t celebrate the second day. He brings a different answer, that the first day is called Chag HaShavuot and the second day is called Matan Torah. However, doesn't necessarily make sense because on the first day, we say that it is Zman Matan Toroteinu in Tefillah.
Maharal explains that both opinions are correct, and that HaShem gave the Torah on the sixth of Sivan, but Bnai Yisrael did not fully receive it. It took them an extra day to comprehend the fact that this gift is really theirs, and therefore both opinions are correct.
Why do we decorate the Beit Knesset with flowers on Shavuot?
The Levush explains that there was grass around the mountain. The Maharishi explains that the flowers bring a pleasant fragrance to elude to the pleasant smell that spread through the world during Matan Torah. We can also say that grass teaches us that one needs to be humble like the grass which is low and trampled upon to learn Torah.
Why do we eat dairy foods on Shavuot?
The Rama says that it is to commemorate the two loaves of bread offered on Shavuot. The Halacha is that one cannot eat the same loaf of bread that was used with meat with dairy. Therefore if someone will eat dairy he will have two loaves, one for meat and one for dairy. Based on the above reason, a person needs to eat two loaves of bread on Shavuot. The Chok Yaakov adds another reason that it says in the Pasuk that milk and honey will be under your tongue. Therefore, we eat dairy foods on Shavuot. Based on this reason, we should also eat honey with milk.
Wishing you all a meaningful and inspiring chag.
Rabbi Eliyahu Tal