What mushroom? What leaf?

Basho, the great Japanese haiku master, wrote 
‘matsutake ya shiranu ki no ha no hebari tsuku’, classically translated as: ‘Matsutake; and on it stuck the leaf of some unknown tree.’ 
[Matsutake is a very highly prized mushroom in Japan - it is not this one*]

The celebrated American composer John Cage, who was a lover of fungi, struggled to find a better translation. Another composer suggested: ‘Mushroom does not know that leaf is sticking to it.’
Cage went away, came back with: ‘That that’s unknown brings mushroom and leaf together.’ He knew it was too heavy-handed.
 Finally he came up with: 
‘What leaf? What mushroom?’

You can hear John Cage talking about this here.

*I thought this might be an orange bonnet but it may be a waxcap.