Last time I checked, it was an executive order to move a drug from schedule 1 to 2 (has medical use).
The Controlled Substances Act would still punish marijuana possession since it is specifically named there, not just in reference to schedule I.
Opium poppies are also listed by name, but while you can grow them in your flower garden (but putting one in a vase on your dining table is a crime!), you can't even grow cannabis.
My point is that posession would still be punishable by law.
(21 USC 841)