Yes it is legal to grow Papaver Somniferum in Washington State.
Is it legal to grow this plant in washington if you only grow it for looks.
As long as you are not harvesting it .its nice to look at makes a hell of a tea but why drink something that makes you want to sleep all day ?
What is the common everyday name of this plant? Oh! Opium...why would you want something that is poisonous if swallowed ...you could end up injuring or killing someone you don't even know....I don't even pretend to know if this is illegal to grow in the united states and I don't intend to find out....later