The magic of growing your own mushrooms | Brief letters

Focus on fungi | Not Robinson Crusoe but The Coral Island | Sleep | Lettuce play with words | Crypto fools and their money

One valuable benefit of purchasing cultivated mushrooms (The world is your oyster mushroom! The expert guide to cooking delicious fungi, 21 February) is that it avoids the worry of poisoning yourself from an incorrectly identified wild sample while reducing excess wild forage collection. Home cultivation is another option, with further benefits of using food byproducts. Fungal spawn is available online and grows well on a mix of cereals and sawdust. Try a local microbrewery for spent grains or a cafe for used coffee to develop your own fungi farm.
Keith Thomas
University of Sunderland

I'm afraid Valerie Smith (Letters, 23 February) has misremembered the gruesome account of the launching of canoes over the trussed, living bodies of prisoners". This is not from Robinson Crusoe but from The Coral Island by RM Ballantyne, which is probably no longer read. I read both books as a child and remember it well.
Pat Parkin-Moore
Croft, Leicestershire