Conker

Quite a few of these have been blown from the horse chestnut tree

Remember playing conkers as a child - must introduce the game to 6 and 4 yo's - they already know the following rhyme

Underneath the spreading chestnut bough
There sat Mary milking a cow
The farmer came up
And gave her the sack
So she turned the cow over
And poured the milk back

Think perhaps I should spend more time in grown up company

Ooops - turns out this is a sweet chestnut