When I first saw the leaves and the yellow flowers (they do mimic dandelions) my first thought was wild lettuce. I have some growing in the back behind the house and I leave it. The first year or two it won't grow tall, but once it matures some it will grow 3-6 feet in height.

Here is a good description and you'll see in the video with the guy kneeling down, the wild lettuce is quite tall
http://www.skilledsurvival.com/wild-lettuce/