Hazelnuts

Of course; these delicious tasting nuts are deeply loved by squirrels too, so if you want to beat them to the ones on the lower, reachable branches you better be there early and pick them when they look like this! Then let them ripen somewhere dry until they become brown and fall out of their cups by themselves :)

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Fun fact: In the old days the hazelnut bushes were considered sacred by people in many European countries. In Norse Mythology hazel is the tree of Tor (Thor) - the thunder god. And it was believed that when eating hazelnuts it would give you wisdom and poetry.