I did some research based on your question. I'd love to see other sources if you have them, but this view seems to come from a sole scholarly source: the 20th century anthropologist Sula Benet. Unfortunately it was difficult to find good sources as most of the results were pro-marijuana opinion pages, but everything I viewed traced back to Benet as the source of this meme.

As for Benet's work itself, there is considerable reason to doubt her methodology and conclusions...I found the following article to be a good critique of her work on this issue:

Does q'nah-bosem mean cannabis?


Ultimately, I wouldn't really be shaken if Benet's assertion really was the case: her conclusion just doesn't seem to be supported by the evidence, and the issue on the whole seems to me a distraction from central issues of faith.