In general, the GRE Literature test does not weight post-1945 literature heavily. The poets below are most likely to appear in a process-of-elimination ID section. It's enough to recognize the names and read the listed poems at least once. (Poems in bold should be read multiple times.)
1. Sylvia Plath
-"Daddy"
-"The Mirror"
2. John Berryman
3. Amiri Baraka
-"Poem for Half-White College Student"
4. Anne Sexton
-"The Truth the Dead Know"
5. Elizabeth Bishop
-"One Art"
6. Robert Lowell (link to GRE Lit Blog post)
7. Gwendolyn Brooks
-"The Mother"
-"Gay Chaps at the Bar"
-"We Real Cool"