To answer the title, I believe in evolution, I dont believe in creation. As for how the world came to be, well, I dont know off hand, but I'm sure I would accept whatever the common scientific concensus is at the moment.

As for weed, it came about like every other living I suppose. Initially from some primitive form of life, which evolved over the course of millions of years. There is no why.

__________________
If god dropped acid, would he see people?