Can you give an example of personification in Phillis Wheatley's "To His Excellency, General Washington"?

Wheatley, a slave who was eventually freed from bondage, wrote this poem in praise of George Washington, and he invited her to meet him as a result. An example of personification, or of giving human qualities to inanimate objects, is Wheatley's description of freedom as a goddess in the following lines:

The Goddess comes, she moves divinely fair, Olive and laurel binds Her golden hair:   Wherever shines this native of the skies, Unnumber’d charms and recent graces rise.

Freedom is personified as a goddess with an olive branch and laurels on her head. The olive branch was a symbol of peace, while laurels were given to the victors in Roman contests.

Later in the poem, Wheatley compares the power of the American armies to the wind: 

How pour her armies through a thousand gates, As when Eolus heaven’s fair face deforms, Enwrapp’d in tempest and a night of storms; Astonish’d ocean feels the wild uproar.

In this example of personification, the wind is personified as Eolus, a God who can upset heaven by making the winds blow. Heaven, or the skies, is also personified as someone with a face. The American armies under George Washington are compared to Eolus's winds, and their strength makes the oceans feel their power. The response of the oceans is also an example of personification, as the waters are able to feel the disturbance caused by the winds.

This poem by Phillis Wheatley, "To His Excellency, General Washington," was written and sent in a letter to General Washington by the author.  Wheatley was obviously inspired by Washington, and his return letter to her is equally complimentary.  Wheatley uses many complex images and allusions, and this poem is no exception.  Your question is about personification, and I found several examples in the first few lines of this poem. 

While freedom’s cause her anxious breast alarms,
She flashes dreadful in refulgent arms.
See mother earth her offspring’s fate bemoan,
And nations gaze at scenes before unknown!

Here, freedom and mother earth have been personified (inanimate objects given human qualities).  Freedom here feels alarm, and she "flashes dreadful"--both human actions which a literal freedom can not do.  Mother earth has children ("offspring") and she "bemoans" (cries out in woe over) their fate. 

If you keep reading, there are plenty more examples of personification in this poem.  The e-notes link below has some other helpful information regarding Phillis Wheatley and this particular poem. 

How does Phillis Wheatley personify the American colonies in "To His Excellency General Washington"?

Wheatley personifies the American colonies as a warrior goddess named Columbia. She wears armor, "flash[ing] dreadful in [her] refulgent arms." Columbia takes up "freedom's cause," moving "divinely fair" with her golden hair and many charms and graces. She leads armies, and she seems to exist always in the "bright beams of heaven's revolving light." Columbia also wears "Olive and laurel" branches in her hair. In Greek mythology, the olive is associated with the warrior goddess, Athena, and Columbia's power and majesty benefits from this association with this most powerful goddess. Further, laurel is associated with the god, Apollo, and is a symbol of victory.

Thus, the symbolism of Columbia's ornaments seems to hint at both her undeniable power and beauty and intelligence, as well as her inevitable victory over Britannia, the personified colonizer: England. When "Columbia's arm prevails," Britannia's head drops, and she accepts defeat, "Lament[ing] [her] thirst of boundless power too late." In the end, then, when Wheatley describes Washington as having "A crown, a mansion, and a throne that shine, / With gold unfading," as a leader with "virtue on [his] side," she associates him with the gods as well, describing him like an Olympian.