More on Not Worth a Rush from Infoplease:

• Not Worth a Rush - Not Worth a Rush (See Rush.) Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894 Related ...
• rush: meaning and definitions - rush: Definition and Pronunciation
• Rush - Rush Not worth a rush. Worthless. The allusion is to the practice of strewing floors with rushes ...
• William Butler Yeats: Michael Robartes and the Dancer - Opinion is not worth a rush; In this altar-piece the knight, Who grips his long spear so to push That dragon through the fading light, Loved the lady;
• Dictionary of Phrase and Fable: N - Definitions, origins, and illustrative excerpts for words, phases, and literary allusions starting with "N"