Rhodesia and Nyasaland (1953-1963)
The Federation of Rhodesia and Nyasaland (also known as the Central African Federation) was a British colonial entity consisting of Northern Rhodesia (now Zambia), Southern Rhodesia (now Zimbabwe), and Nyasaland (now Malawi). It was intended to become an independent dominion within the Commonwealth, but Nyasaland and Northern Rhodesia opted to secede, becoming independent states with majority rule shortly thereafter.
Of the three symbols featured on the coat of arms, only the sun (representing Nyasaland) is still in use on a flag. Initially described as a setting sun, it was changed to a rising sun when Malawi became independent in 1964, and since 2010 it has been a fully risen sun.
You can see a photo of a real flag of the federation here.