The command:
/give @p banner 1 0 {BlockEntityTag:{Base:15}}
Will give you a black banner. Though "Patterns" still works. For example:
/give @p banner 1 0 {BlockEntityTag:{Base:15,Patterns:[{Pattern:moj,Color:15}]}}
Would give you a black banner with a white pattern.
This does not apply to shields.
Banner items use tge data value, not the base tag.