Countee Cullen was one of the first literary stars of what's known now as the Harlem Renaissance (circa 1919-1934), and although his reputation dwindled after that, it recovered, and he is arguably one of the best lyric poets the U.S. has produced. His sonnet, "Yet Do I Marvel," is perfect, blending a formal but contemporary idiom with the form and crafting a superb "argument" about race, color, theology, and existentialism--without ever getting heavy, and with a light ironic touch. It's just one of those poems you can admire forever.
There's a nice anthology of Cullen's poetry--and one novel--edited by Gerald Early: My Soul's High Song.
Eventually, Cullen pursued middle-school teaching as a career--in Harlem, where James Baldwin was one of his students.
Here is a link to more information about Cullen: