Federal agents struck at the heart of California's medical marijuana movement, raiding the nation's first pot trade school and a popular dispensary, both run by one of the state's most prominent and provocative activists, Richard Lee. The raids in Oakland by the Internal Revenue Service and Drug Enforcement Administration sent a shudder through the medical cannabis trade and angered the plant's devotees, who believe the federal government is trampling on California law and the wishes of voters who approved medical marijuana use nearly 16 years ago.