The most common graveyard poet on the GRE is Thomas Gray, whose Elegy Written in a Country Churchyard (1751) is very likely to appear on the test. Here’s an except:

The curfew tolls the knell of parting day,
The lowing herd wind slowly o’er the lea
The plowman homeward plods his weary way,
And leaves the world to darkness and to me.

Now fades the glimm’ring landscape on the sight,
And all the air a solemn stillness holds,
Save where the beetle wheels his droning flight,
And drowsy tinklings lull the distant folds;

Save that from yonder ivy-mantled tow’r
The moping owl does to the moon complain
Of such, as wand’ring near her secret bow’r,
Molest her ancient solitary reign.

Listen to the audio file of Elegy Written in a Country Churchyard, and be able to identify it when you see it.