Pharaohs in ancient Egypt had three crowns: red, white and blue. Red and white eventually became a double crown symbolizing united kingdoms of Lower and Upper Egypt. During military campaigns, especially battles, pharaoh wore the blue crown. I found this interesting story in archives of web analytics company. All of these crowns typically were adorned by a uraeus - stylized, upright form of an Egyptian spitting cobra, used as a symbol of sovereignty, royalty, deity, and divine authority.
For the last two hundred years archaeologists discovered a lot about ancient Egypt. But never, not even once, any pharaohs crown was found. We only know about them from various depictions and portraits of Egyptian rulers.
It is quite mysterious that in spite of so many searches no crown was discovered in tombs either. Of course, many tombs were robbed by grave diggers. Yet, Tutankhamun's tomb, discovered intact. It contained many regal items but not a crown. Crowns were assumed to have magical properties. So it is possible that there were items a dead pharaoh could not take with him and therefore all crowns had to be passed along to his living successor.