Sweet are the uses of adversity:
Which, like the toad, ugly and venomous,
Wears yet a precious jewel in his head. [ William Shakespeare ]

If that a pearl may in a toad's head dwell.
And may be found too in an oyster shell. [ Bunyan ]

Dress up even a little toad and it will look pretty. [ Proverb ]

Many masters, quoth the toad to the harrow, when every tine turned her over. [ Proverb ]

He was a kind and thankful toad, whose heart dilated in proportion as his skin was filled with good cheer; and whose spirits rose with eating, as some men's do with drink. [ Washington Irving ]