Which of the following poems is not in rhyme?

From the poems provided, the one which is not in rhyme is 'Fog', a poem by Carl Sandburg. This poem first appeared in Sandburg's first mainstream collection of poems, "Chicago Poems", published in 1916.

Sandburg took several opportunities to publicly describe the genesis of the poem. He stated that at one point when he was carrying a book of Japanese Haiku, while on his way to meet a juvenile court judge, he had cut through Grant Park and saw the fog over Chicago harbor. He had seen many fogs before, but this time he had to wait forty minutes for the judge, and he only had a piece of newsprint handy, so he decided to create an "American Haiku". Haiku is a traditional form of Japanese poetry. Haiku poems normally are made up of 3 lines. The first and last lines of a Haiku have 5 syllables and the middle line has 7 syllables. The lines rarely ever rhyme.

The poems 'Little Boy Blue' (1888) by Eugene Field, 'Stopping by Woods on a Snowy Evening' (1923) by Robert Frost, and 'Paul Revere's Ride' (1860) by Henry Wadsworth Longfellow are all done in rhyme form.