My grandmother's favorite--Lantana is so easy to grow. It attracts butterflies, loves sun and can tolerate drought. Good watering results in a showy and large plant. Freezes to the ground in winter but returns year after year.
Good idea for multiple reasons: equisetum (horsetail, snake grass, puzzlegrass) (grow zone grows so quickly and make even the newest newbie of a gardener feel accomplished and happy. equisetum can get out invasive and a container will control it.