This word pair surely marks one of the first times I became aware of homophones. (Although, I suppose, if I'm going to be honest, it was more likely "but"and "butt.") To this day, it's one of the first homophone pairs that springs to mind when someone asks for an example, right behind "bare" and "bear."
In fact, given my love of illustrating animals, I should compile all the animal homophones together sometime – hare, ant, moose, horse, bear, mussel, boar, deer, ewe/ewes, flea, gorilla, lynx. Gulp, I guess I've got my work cut out for me.
Any I'm missing? Jay? Hart? Oooh, I may have to go back and revise "rays." Dang.