"Why not?" said Matt Cassel the quarterback.
A homophone for a speck is "spec". A homophone for "trench around a castle" could be "moat".
speck:motetrench around a castle:moat
The answer is that there is no homophone for can, but can is a homonym.
Him is the homophone for hymn.
Your is a homophone of you're. In some dialects, yore is another homophone.
the homophone for stationery is stationary
The homophone is dense.
The homophone is cell.
The homophone is ail.
there is no homophone for length
The homophone is taught.
stock homophone