I'm not really convinced that the picture identified as a dandelion is actually a dandelion. That is the problem with plant ID - without the entire plant, it's difficult, at best, and possibly dangerous, to tell what it is. Better to get a good plant ID book, with actual photographs, detailed descriptions, and information on how to tell it from similar plants. Once you have them identified, look them up online to see if they are edible or have other uses.
I'm guessing you're in Florida. Here is what looks like a good site for plant ID, specific to your area~
http://www.fnps.org/pages/plants/landscape_plants.php