The device of Clovis was three toads (or botes, as they were called in Old French), but after his baptism the Arians greatly hated him, and assembled a large army under King Candat to put down the Christian king. While on his way to meet the heretics, he saw in the heavens his device miraculously changed into three lilies or on a banner azure. He had such a banner instantly made, and called it his liflambe. Even before his army came in sight of King Candat, the host of the heretic, lay dead, slain, like the army of Sennacherib, by a blast from the god of battles. (Raoul de Prèsles: Grans Croniques de France.)
“It is wytnessyd of Maister Robert Gagwyne that before thyse dayes all French kynges used to here in their armes iii Todys, but after this Clodoveus had recognised Cristes relygyon iii Floure de lys were sent to hym by diuyne power, sette in a shylde of azure, the whiche syns that been borne of all French kynges.” —Fabian's Chronicle.
The toad, ugly and venomous, wears yet a precious jewel in its head. Fenton says: “There is to be found in the heads of old and great toads a stone they call borax or stelon, which being used as rings, give forewarning against venom (1569). These stones always bear a figure resembling a toad on their surface.” Lupton says: “A toad-stone, called crepaudia, touching any part envenomed by the bite of a rat, wasp, spider, or other venomous beast, ceases the pain and swelling thereof.” In the Londes-borough Collection is a silver ring of the fifteenth century, in which one of these toad-stones is set. The stone was supposed to sweat and change colour when poison was in its proximity. Technically called the Batrachyte or Batrachos, an antidote of all sorts of poison.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894
More on Toads from Fact Monster: