Deuteronomy Chapter 16 - In this chapter we are reminded about some of the special holy days set aside by the ancient Israelites. In particular, there are three great festivals in which Jews and Israelites should meet at the temple and celebrate.
The Feast of Unleavened Bread is celebrated during the month of Abib, which is a month in the Hebrew calendar. It's to remind the Israelites about their escape from Egypt. In 16:3 it says that you must eat unleavened bread for seven days; and in 16:8 it says six days, so I'm not sure what that's about.
The Feast of Weeks is meant for the entire community of ancient Israelites, and it is to remind them that their people were once bondsmen of Egypt.
In this chapter, it's not clear what The Feast of Tabernacles is about, but elsewhere on the web it says it's agricultural in origin.
During these festivals, or holidays, the males of the tribe must present themselves before Yahweh, and give a generous donation to the priesthood.
I'm not sure why it's in there, but at the end of the chapter (16:16), it almost sounds like judges and officers are picked during these festivals as well.
It's an interesting chapter and there's nothing too controversial. It's actually interesting to learn about the holidays of other cultures as well.