Homonyms

There are many homonyms in the English language.

where & wear

eight & ate

know & no

One & won

two & too & to

reed & read

Sun & son

I & eye

Can you think of any others?

These are usually called homophones, I think, and there are literally hundreds of them. You can have a look here:
http://www.bifroest.demon.co.uk/misc/homophones-list.html
http://www.learnenglish.de/homophones/Homophones.htm

Besides, there are homographs, e.g. "lead (to be a leader)" - "lead (metal).

As for the real homonyms, I can remember only "spring (season, kind of brook, spiral coil)

Threre's the famous one:

air, err, heir, ere, e'er, aire (and a few other obscure words).

(This is in US English)