More on Not Worth a Straw from Infoplease:

• Not Worth a Straw - Not Worth a Straw (See Straw.) Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894 ...
• Rush - Rush Not worth a rush. Worthless. The allusion is to the practice of strewing floors with rushes ...
• Straw - Straw Servants wishing to be hired used to go into the market-place of Carlisle (Carel) with a ...
• Dictionary of Phrase and Fable: N - Definitions, origins, and illustrative excerpts for words, phases, and literary allusions starting with "N"