Really it might be that for gardeners the most interesting plantations would be those in disrepair, with the grounds gone to seed, so to speak, as there likely would be plants which have naturalized from the original gardens.
In WV there were not plantations in most of the state, but around old farmsteads one can find all sorts of flowers and medicinal herbs once grown in the gardens.
Of course I likely need not mention that in VA are 2 old plantations with the experimental gardens of Washington and Jefferson maintained and very interesting: Mt. Vernon and Monticello.