Robert Burns (1759-1796) was a Scottish poet influential in the beginnings of the Romantic movement. He wrote poems in English, Scots, and Scottish dialect. Outside of Scottish and literary circles, he is best known as the author of "Auld Lang Syne."
Don't spend too much time on Burns--if you see Scottish-looking spellings, and Burns is a choice, pick him. However, it is worth at least skimming the following poems before the GRE Literature exam, and some of them are quite fun to read.
1. "A Red, Red Rose"
2. "Tam O'Shanter: A Tale"
-long; written in Scots; link goes to summary
3. "Ae Fond Kiss"
-Written in Scottish dialect
4. "Scots Wha Hae"
-Written in Scots; was an unofficial national anthem of Scotland