Epping Forest stretches from Manor Park to Epping and covers around 8,000 acres (3,237 hectares).
Haines said it was one of the country’s most important habitats for fungi and many species depended on being left undisturbed.
She added: “If somebody clears mushrooms from the bottom of a tree, they stop feeding the tree nutrients.
“We want everyone to enjoy the forest and experience its remarkable wildlife. Our message is simple – click, don’t pick.”
The City Corporation, which manages Epping Forest as a registered charity, said its open spaces had been home to several significant fungi discoveries in recent years.
In 2024, a new species of mushroom, Hydropus inopinatus, was discovered in Burnham Beeches, Buckinghamshire.
In 2025, the UK’s first confirmed record of a rare fungus species, Russula blumiana, was made in Epping Forest.
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