Central Intelligence Agency World Factbook.
The line drawing in the center shows a mosque, the year the country won independence from the United Kingdom, wheat and a scroll with the country's name. The green is described as representing agriculture, prosperity and Islam.
After the Taliban were defeated and Hamid Karzi was elected in 2004, the flag was adjusted slightly - the wording on the scroll was revised from "The Islamic Republic of Afghanistan" to "Afghanistan," explains Worldpics.com.au
The image of the flag, courtesy of CIA World Factbook.