Natalie Jones Bonner, a 58-year-old entrepreneur in Biloxi, Mississippi, who has used cannabis to reduce inflammation in her knees and wrists, wanted her fellow Mississippians to experience the drug’s medical and economic benefits. So she volunteered to collect signatures for a ballot initiative to legalize its medical use. But the Navy veteran, who is black, was disheartened to discover that the campaign included few African-Americans. Mississippi is 38 percent black — the highest percentage in the nation — but four white people were leading the campaign. And people of color made up less than a third of the 70 people on the steering committee.