I've found that the only kind of legal weed that grows naturally in the UK is grass.
The UK laws are quite good with regards to power plants I think, those that are indigenous to the country rather than invaders are free to consume, whereas more recent "immigrants" are caught up in business.
There used to be a grey area in Camden Town (London - UK) with a trade in non-indigenous mushrooms, but that was closed down some years back I think, haven't been there in a while,
What are the I's impressions of Ammsterdam, my own feeling was that many of the coffee shops had no business ethics, being only interested in the money, but the smart shops were good, although unfortunately also closed now by my understanding,
No idea about collymen in Jamaica, the only impressions I have of the trade there are from the film "THe Harder They Come" which is several years old now, have things improved?