With a non-profit, you would be looking for donations. I imagine many fundraisers would be leery of pursuing donations through existing channels for fear of the legitimacy of the tax deduction for medical cannabis.
I am less familiar with the internal state/federal differences on the treatment of cannabis. I would suggest that you confirm that deductions to this organization would be eligible for typical 501c3 tax deduction treatment and then pursue fundraising organizations, preferably through reference of organizations in the same or similar space. You can check online through guidestar to see nonprofit organization financials. They should highlight fundraising expenses and then network through to see.