Double Poppies, St-Johnswort and Valerian

I am looking for an ornamental poppy which has double flowers, is perennial and is medicinal. People have told me, such a poppy is common in Europe.

The only poppies that are used in medicine are the opium poppy (Papaver somniferum) and the corn poppy (P. rhoeas), and both are annuals. Sometimes a third annual, P. dubium, is used as a substitute for the corn poppy. We are not aware of any perennial, double-flowering poppy used in medicine.
The opium poppy can persist over the years, by reseeding itself. Perhaps your friends are referring to this variety. It can come in an ornamental double-flowering form. Opium poppy was for centuries a commonly used folk medicine taken in syrup from as a sedative. It was unequalled as a remedy to calm the nerves. We have heard of stories, however, of its unwitting abuse in settling down newborn babies. Harried mothers in central European countries used the syrup to quiet crying babies, causing mental retardation in many cases where the remedy was used inappropriately.

Could you send me information on St-Johnswort and valerian production?

Both St Johnswort and valerian can be grown in temperate climates, in full sun and in well drained soil. Both are grown commercially throughout North America. Seeds are started in seedflats or plugtrays. Field spacing is 60-80 cm (2-3 ft) apart for valerian and 30 cm (1 ft) apart for St Johnswort. Typical yields for valerian are 10 tonnes fresh root per hectare (4 tons/acre) or 2.5 tonnes/ha dry weight (1 ton/acre). For St Johnswort, the 'Topas' variety produces 2.5 tonnes/ha dried herb.