What your mom {probably} never told you about mulberry plants is that you can get high from ingesting the white sap in all parts of the plant except the ripe fruit.

Mulberries – Red, Black & White – WARNING: Do not eat the unripe fruit and leaves because they may be mildly hallucinogenic. Ripened fruits are very edible.
Native American Medicine: Alabama [Indians] infused roots and drank as a stimulant for increased energy.
Unripe fruit and green parts of the plant have a white sap that is intoxicating and mildly hallucinogenic.

Information found @ Erowid & Wikipedia

Sounds an awful lot like Ecstasy to me!! :O