The use of white bryony (Bryonia dioica) as a substitute for mandrake (Mandragora officinarum) has been discussed elsewhere on this website.  Since that was written the following account has been found in the eighth (1768) edition of Philip Miller’s Gardeners Dictionary:

‘The roots is this plant have been formerly, by impostors, brought into a human shape, and carried about the country, and shewn for Mandrakes to the common people, who were easily imposed upon by their credulity, ammd these got good livings thereby.  The method which these people practised, was to find a young thriving Briony plant, then they opened the earth all round the plant, being careful not to disturb the lower fibres; and (being prepared with such a mould, as is used by the people who make plaster figures) they fixed the mould close to the root, fastening it with wire, to keep it in its proper situation; then they filled the earth about the root, leaving it to grow to the shape of the mould, which is effected in one summer; so that if this be done in March, by September it will have the shape.’