Although the Scottish poet Robert Burns was most definitely not Wiccan, and wasn't Pagan either, his work is well known in today's Pagan communities. Prior to his untimely death at age 37, Burns created a number of complex poems filled with lyrical imagery describing nature and pastoral scenes. On January 25, the anniversary of Burns' birth in 1759, many people of Scottish descent celebrate "Burns Night," which includes lots of drinking, singing, Scottish foods, and readings of Burns' works.
Poems by Burns which are well-known to many Pagans include Corn Rigs and Barley Rigs which tells of two lovers at Lammastide, Hallowe'en, which describes prophetic visions by country-folk, and of course The Ballad of John Barleycorn. Burns was quite prolific, and wrote hundreds of songs and poems during his short life. He is regarded as a pioneer of the Romantic literary movement.
For a complete list of poems and songs, see Burns Country.