No. Possessing marijuana is illegal in the United States regardless of religion. In fact, while a number of states have taken steps to decriminalize marijuana use, particularly for medical reasons, federal agencies can still arrest marijuana users within those states.
Many compare the Rasta use of ganja to the Native American use of peyote, which is legal in certain religious circumstances despite the fact that both ganja and peyote are Schedule I drugs, which are the most highly controlled substances.
Read more: Legality of Marijuana by Country