The original's reference to "poppies" was likely referring to dried and preserved poppy pods, not the fresh flower. So although poppy seeds are not quite right,

The original's reference to "poppies" was likely referring to dried and preserved poppy pods, not the fresh flower. So although poppy seeds are not quite right, it's the closest you can get without moving into a legal (and medical) gray area, since poppy pods can potentially contain a pretty significant amount of residual morphine and thebaine alkaloids.