1ce: I'm not sure any psilocybes produce phenethylamine, personally, there is only one paper stating they found PEA as a decarboxylation product of phenylalaine but the results have not been confirmed by any other studies (especially not by actual mycologists). My interpretation is that perhaps the liberty cap samples were contaminated by grass root exudate or organic material such as cattle urine/manure which contained phenethylamine.
see paper here
http://jat.oxfordjournals.org/content/22/1/45.full.pdf
ND: don't be so literal about poppies. Indeed they do heal the earth. Seeds of poppy family can be dormant in the ground up to 80 years! They are a very intelligent and sensitive plant, knowing when is best for them to germinate and prefer soils which are relatively not as fertile and can grow in soils which are extremely compacted when not much else will. This is what qualifies them as a pioneer plant and are very capable of aerating a 'broken' piece of land within a growing season or two, opening the field to other less hardy plants quite quickly and drawing up water as well as creating a much cooler, moister microclimate when colonizing (reverse-albedo effect). Are you familiar with the concept of ecological niches and succession?