Elsewhere on this website it has been noted that Oxalis tetraphylla, four-leaved pink-sorrel (also known as iron cross), is sold as ‘lucky clover’ or ‘four-leaved clover’, even though it’s not related to clovers, Trifolium spp.  An apparently new alternative name is ‘good luck plant’, under which name it is currently on sale at Neal’s Nurseries Garden Centre, Heathfield Road, in the London Borough of Wandsworth.