Old fashioned ground cover name?

[Nita]

I don`t know the name of the yellow plant, but it reseeds itself real fast.  It was in some wildflowers I planted one year, and it just kept spreading.  I have to thin it out every year.  I have another ground cover with purple flowers.  I think it is called creeping myrtle.  But it is real thick and takes over the area.  It is in an area we don`t mow.  

[Petee]

here is a close up pic

You know Bon that could be the same plant.  Someone identified it positively for me and it Cypress Spurge, mildly invasive but great to grow on impossible to vegetate cliffs!

http://www.google.com/imgres?imgurl=http://www.ppws.vt.edu/scott/weed_id/cypressspurge4-25b.jpg&imgrefurl=http://www.ppws.vt.edu/scott/weed_id/ephcy.htm&h=358&w=509&sz=207&tbnid=e1IdmK6ntCp9RM:&tbnh=92&tbnw=131&prev=/images%3Fq%3DCypress%2BSpurge&hl=en&usg=__OLM9kqqNmc-Fapm8rppnuCx5I9o=&ei=CbX6S92FMYL58AbEwpjkCg&sa=X&oi=image_result&resnum=3&ct=image&ved=0CAoQ9QEwAg