Poems suitable for memorial services tend to be poems that focus on the subject of death. Generally speaking, these kinds of poems fall into two categories: poems of mourning, and poems asserting the triumph of life.
Poems in the former category include Robert Frost's "Nature's First Green is Gold," which is suitable for the death of a young person. Other poems include elegies like Allen Ginsberg's "Kaddish" and Tennyson's "In Memoriam." In contrast, the first stanza of Dylan Thomas' "And Death Shall Have No Dominion" and John Donne's "Death, be Not Proud", both assert the failure of death in the face of life.