Plant Story--Pretty, Aggressive Creeping Jenny, Lysimachia nummularia

 Some places in the U.S., creeping Jenny (Lysimachia nummularia, primrose family Primulaceae) is a weed, some places a ground cover. 

This is a low spreading plant with pretty round bright green leaves and yellow flowers. It is perennial and evergreen. In my yard it makes a nice ground cover in the shade without being particularly aggessive. In much of the U.S., though, it grows much better, making it a weed.