There is a great deal of imagery in Shakespeare's Romeo and Juliet. When trying to find examples of imagery in this or any other Shakespeare play, it is a good idea to look to the major monologues. In these speeches, characters are generally alone as they examine their own emotions, which allows imagery and poetic language to abound.
In Romeo and Juliet, some prime examples can be found in Mercutio's "Queen Mab" speech in act 1, scene 4, and in several of Juliet's monologues: in "Gallop Apace" in act 3, scene 2, she entreats nighttime to come faster so she and Romeo can consummate their marriage. In doing so, she employs lots of imagery of light versus dark and night versus day. In her "What if this mixture do not work at all?" monologue in act 4, scene 3, in which she fears she will either die from Friar Lawrence's potion or wake up too early in her family's tomb, she uses lots of death imagery to express her fears.
A specific example from Mercutio's speech, in which he argues that Romeo's lovestruck condition is a result of magical fairy interference and digresses about several long folkloric tangents, might be as follows:
Her wagon-spokes made of long spiders' legs,
The cover of the wings of grasshoppers,
The traces of the smallest spider's web,
The collars of the moonshine's watery beams,
Her whip of cricket's bone, the lash of film,
Her wagoner a small grey-coated gnat,
Not so big as a round little worm
Prick'd from the lazy finger of a maid;
Her chariot is an empty hazel-nut
Made by the joiner squirrel or old grub,
Time out o' mind the fairies' coachmakers.
And in this state she gallops night by night
Through lovers' brains, and then they dream of love;
Here, you can find an abundance of nature imagery as Mercutio paints a picture of how the fairy, Queen Mab, gets around.