We have compiled data on 15 taxa (5 woody and 10 herbaceous) as established (9 taxa) or adventive-waif species (6 taxa) in Maryland (2 taxa) and Virginia (13 taxa) that are not considered definitive elements of each state's extant flora. The woody taxa are Acer ginnala, Corylus avellana, Pyrus betulifolia, Tilia cordata, and Vaccinium virgatum. The herbs include Crocus tommasinianus, Daucus pusillus, Dracocephalum parviflorum, Euphorbia mercurialina, Indigofera hirsuta, Opuntia engelmanni var. lindheimeri, Pilea microphylla, Polycarpon tetraphyllum, Saxifraga stolonifera, and Silene flos-cuculi spp. flos-cuculi. We provide updated taxonomic information, range clarifications, supplemental habitat data, and other details about our voucher specimens and other collections.