Symbolism is "in its simplest terms, a symbol is anything that stands for or represents something else beyond it."(http://www.symbolism.org/writing/books/sp/1/page2.html)
Rice is a symbol of fertility, and as such rice is traditionally thrown at the bride and groom at weddings so they will have children. I don't know if that symbolism is in the Bible, but it is definitely a part of traditional Western culture.
Purple is a symbol of royalty, and as such in many stories, including biblical ones, a king's or queen's robe is purple.
The dust that is in the NT is when Jesus told His disciples to wipe the dust off their feet if they encountered people, or an area, that did not want to hear about His teachings. However, that is not symbolism. Dust doesn't mean anything but dust.