This weed sprawls everywhere in my main iris bed. The irises have not bloomed since we moved in and so these offer little velvety spirals of purple color. They are a weed, however–meaning, they might end up becoming a nuisance. I might regret not pulling these out later.
They are in the mint family, and can look somewhat upright or sprawl along the ground. This year (2007) they appeared in early March and seem to be disappearing in the beginning of April.
Dave’s Garden link: Henbit