Manihot grahamii / Hardy Tapioca / Graham's Cassava: a native of Eastern South America, from Brazil through to Argentina. I've done a quick web search and this has been successfully grown as far north as North Carolina. (This photo said it was taken in the Pacific NW).
Zantedeschia aethiopica 'Crowborough' arum lily - Unusual, pure white hood-shaped flowers that are up to 10-15cm (4-6in) long are produced from late spring to mid-summer. It makes a striking architectural clump with lovely arrow-shaped, glossy dark green leaves. It looks great grown beside water as a marginal plant and can be left outside in most frost-prone areas if it is given a deep winter mulch.
Teacup plant from Chile - grows 5 feet tall: This curious plant is a half-hardy perennial that sports white cup-like flowers. Coloration is unique to each flower and acts as an attractant to pollinators, such as bees and hoverflies, much in the same way as can be seen in foxgloves, making it great for wildlife enthusiasts.