KUFI

A 'kufi' is a short rounded cap, traditionally worn by Muslims.
Within the United States, it has become more commonly identified with persons of African descent, who wear it to show pride in their history and their religion. Often made of kente cloth or crocheted in a variety of yarns, kufis became popular fashion items throughout hip hop culture during the late-1980s/early-1990s.
The companions of Muhammad were never seen without their heads being covered. In order to emulate their actions, and thereby approach closer to being correct in their actions, Muslims throughout the world wear a variety of kufis, caps, and other headgear. Another goal of wearing a kufi is to be more like Muhammad and therefore obey and follow his tradition. Kufis, therefore, are not a modern invention within the US-based Muslim community, but a tradition from antiquity. In fact ancient Arabs had the habit of always wearing something on their heads. They considered it inappropriate not to wear headgear such as a turban.
Rapper Nas can be shown wearing one in his music video for his single One Mic
Go to here to see a fatwa about the kufi.