More on Cob-nut from Infoplease:

• Cob-nut - Cob-nut A nut with a tuft. (Welsh, cob or cop, a tuft; German, kopf, the head.) Source: Dictionary ...
• cobnut: meaning and definitions - cobnut: Definition and Pronunciation
• Dictionary of Phrase and Fable: C - Definitions, origins, and illustrative excerpts for words, phases, and literary allusions starting with "C"