Le and les are fairly tricky in spoken French. Most of the time the "s" is silent, so they sound exactly the same. The rule for pronouncing the "s" is the same as the English rule for using "a" versus "an". When the following word starts with a vowel, a "y", or an "h", you pronounce the "s".
So preceding "Shrooms", or "Mushrooms", or even "Fungi", "Le" would sound the same as "Les".
