Helen, that's a very hard (but good) question for me to be able to properly answer it....but I'll try to explain, anyway
The whole thing is like an offering presented in worshipping our predecessors (not only limited to our relatives but also any great people in our history).
There are basically 4 contents in that footed tray. The left side is a garland mainly comprised of jasmines.
For the right side, the top one is what I do not really know what it is (shame on me!). The rest is betel (the leave part) and betel nuts. Both are the products from betel palms. According to Webster's New World Dictionary, both are chewed together by "some Southeast Asian people as a mild stimulant." In the present day, I think it is quite rare to see some people taking these things but still these things including a way of taking them do still exist. Perhaps, it's like when some people are addicted to chewing gums.
Regards, Joe