Yes, I know of mulberry leaves (when young) are edible cooked. And quite delicious. Certainly no hallucinogenic effect. With the Siberian Elm and Mulberry leaves, yes, I know that eating them, and as you say even feeding them to goats isn't
enough of a use. I am really interested in where fertility starts in the cycle of life, and using something like elm or mulberry to fuel your system (comfrey is similar) is something I am really looking into. Using dried or fresh leaves in your tank instead of fish to provide the fertility for hydroponic/bioponic plants is about as
sustainable as I can think of. Even if you are using compost tea, which I am really big fan of, you need to start with something sustainable in order to create sustainable compost, like Siberian elm leaves. However, when composting, most of the
carbon is lost as C02 into the atmosphere. My 5 foot compost pile just finished, and it was barely a little hump on the ground, barely a foot tall when I went to use it. Imagine if we could get the fertility directly from the uncomposted leaves and such! I am very excited to try this out.