-One who goes to sleep after Alos Hashachar Shavuos morning (or on any day) does not say the bracha of Hamapil. Shulchan Aruch w/Mishnah Brurah 239:1MB8, Piskei Tshuvos 494:5
-There is a well known minhag to bring flowers into shul and one’s home as a remembrance that on Shavuos we are judged on “Peiros Ha’ilon” – fruits. However, one should not cut off branches from fruit bearing trees for this purpose because of the Torah prohibition of “Ba’al Tashchis”.
Shulchan Aruch w/Mishnah Brurah 494:3, Piskei Tshuvos 494:10