Sphagneticola trilobata

When this flower is introduced as ground cover in gardens, it quickly spreads vegetatively, not by seed usually. It also creates a mat which smothers many other plants. It has vivid yellow flowers which may attract insects but, it is gardeners who are probably to blame for its prevalence around the world.

It's sometimes called a daisy because its petals arrange themselves in a disc like display, but when I look at it, I find the vivid yellow more reminiscent of a dandelion despite the difference in petal formation.