CALIBAN:
Be not afeard; the isle is full of noises,
Sounds and sweet airs, that give delight and hurt not.
Sometimes a thousand twangling instruments
Will hum about mine ears, and sometime voices
That, if I then had waked after long sleep,
Will make me sleep again: and then, in dreaming,
T111che clouds methought would open and show riches
Ready to drop upon me that, when I waked,
I cried to dream again.

I just looked it up. It's from Act III, Scene ii. The complete text of the play can be found at
http://www-tech.mit.edu/Shakespeare/tempest/full.html
.

It's not a poem. It's a short speech that the character Caliban gives in Shakespeare's The Tempest, a part that Richardson had done on stage at the Old Vic before making this movie.