All three of the poetic elements you mention (alliteration, exaggeration, and personification) can be found in Robert Frost's poem "Stopping by Woods on a Snowy Evening."
Alliteration is, of course, the repetition of initial (beginning) consonant sounds, and examples of it can be found in nearly every line of this poem. (Sometimes it is easier to recognize alliteration and its close relative consonance by reading lines aloud, as there are multiple ways to achieve some sounds.) Note the examples of alliteration (which I have put in bold print) just in the first stanza:
Whose woods these are I think I know.
His house is in the village, though;
He will not see me stopping here
To watch his woods fill up with snow.
The consistent use of the initial -S, -Th, and -W sounds is alliteration. Notice that whose actually belongs with the "H" words, since it is the sound and not the letters that create alliteration.
Exaggeration is a little more difficult to find, because it is quite possible that what the speaker says is true; however, these two examples seem to be a bit hyperbolic (exaggerated for effect):
The darkest evening of the year
And miles to go before I sleep,
And miles to go before I sleep.
It is the superlatives in the first one (darkest evening of the entire year) and the repetition of the second (miles and miles) which suggest they are at least somewhat exaggerated.
Personification is giving human qualities to something non-human or non-living, and the only real example of it in this poem is the horse who can "think" and "ask."
My little horse must think it queer
To stop without a farmhouse near
Between the woods and frozen lake
The darkest evening of the year.
He gives his harness bells a shake
To ask if there is some mistake.
This is a poem full of many poetic devices, among them alliteration, exaggeration, and personification.
In the third stanza, you find the most Alliteration, i.e. repetition of a consonant sound at the beginning of words, "He gives his harness bells a shake" there are also examples in the first and fourth stanzas "His house is in the village though," "To watch his woods fill up with snow," and "The woods are lovely, dark and deep."
Personification is found in the second and third stanzas, ascribing human emotions to the horse: "My little horse must think it queer|To stop without a farmhouse near," and "He gives his harness bells a shake|to ask if there is some mistake."
Exaggeration is found dotting the poem. "Watch his woods fill up with snow," and consider the trees are at least 20 feet tall. "The Darkest evening of the year," how can that be measured. "The only other sound's the sweep|of easy wind and downy flake," these sounds would be hard to specifically isolate.