Dandelion drives the water out of your body ,because it is diuretic and also mildly laxative.It is also used as liver tonic.
Leaves are more diuretic than flowers .Green parts can be used for salads ,they contain a lot of potassium ,vitamin C,A and K.
I would suggest to pick the most green young leaves for salad ,the older ones can be bitter.The root is used to make so called dandelion coffee.Flowers are traditionally used for dandelion wine making.The milk sap from the flowers is used to treat warts in similar fashion as the fig sap.
Warning :People who are taking the blood thinning drug Coumarin should not use dandelion at all ,because it contains too much Vitamin K, which will knock out the effect of the drug.Do not overdo the dandelion coffee either or you can get a dull headache if you are sensitive.
Overall despite it is seen as obnoxious weed ,the entire plant has herbal uses along with magical uses (wish spells).
It is such a pity that the old herbal knowledge has been lost due to modernization.
Do not just mow over the "weeds", but get to know them and to use them if you can.We should not waste a thing.