Like dandelions, ragweed is a weed with a yellow flower. The city no long sprays for dandelions and personally I think they're happy weeds. This other yellow weed however has the potential to make many people unhappy. While the picture looks innocent enough, many people suffer from hay fever due to the presence of this weed. Luckily for me, I'm not one of those people so I was able to get close enough for the picture.
Correction: Seems I need to brush up on my weeds. Thanks to Susan I now know that this plant is NOT ragweed but goldenrod, which is also labeled as an allergy irritant. It does bloom at the same time as ragweed and some say that although it's blamed for allergies, its pollen is too heavy and sticky to be blown around in the wind. Some suspect that since it blooms at the same time as ragweed its the ragweed that is at fault. Hmmm, so much to learn.