The poison is present only in a specific species of almond, namely the “bitter” ones, which are a broader and shorter version of the sweet almond. Although each bitter almond only contains tiny amounts of cyanide, the substance is dangerous enough that it is illegal to sell raw almonds in the US. Nowadays all almonds must be processed through heating in order to eliminate germs and render the poison harmless.
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Off the top of my head: Mustard, Rhubarb, Salt, Liver, and the ever dangerous Dihydrogen Monoxide.