So far my research gives me the answer 'immature white mulberry leaf' but the answers were not from 'official tree people', only from blogs and forums.
As a rule, unless the poster is known to me I tend to mistrust those. But chelle has the actual tree so I believe her.
The dried, powdered leaves of the mulberry can be used as tea. I will take cuttings, even though this is the wrong time of year, and it they root for me I will keep the tree small, either coppiced or pollarded and harvest the young leaves.
On second thought, probably pollarded as my dog might pee on the coppiced tree leaves.
