carat, carrot, caret, karat
carat means a unit of weight for precious stones
carrot means a root vegetable
caret means the character printed when shift+6 is pressed on a keyboard
karat means a measure of the purity of gold

carol, carrel
carol means a song of joy
carrel means a library study cubicle

cast, caste
cast means a stiff support for a broken limb
caste means a hereditary social class