This is the flag of Nigeria (on a belt buckle).
Green to represent the forests and white to represent peace. Apparently it was first used in 1960 on Nigeria's Independence Day. (You can read more on this flag at Wikipedia).
Approx 85mm wide & 60mm high.
The red, gold and green are the colours of Pan-African Unity (also the colours of the Ethiopian Flag but upside-down). The lion of Judah with its crown and pennants sits...