Burdock- a minor antioxidant.
Dandelion greens- recommended as a salad ingredient.
See Mayo Clinic on line.

The concept of flushing toxins with herbs is largely nonsense; a big money-maker for the herbalist snake oil salesmen.

Drinking enough water is sufficient. Men should take in about 3 liters per day and women 2.2 (normal activity); remember that 20% of this comes from food in a normal diet. Greater activity, heat and high altitude cause more water loss, which should be replaced.
Recommendations of the Institute of Medicine; see Mayo Clinic articles: http://www.mayoclinic.com/health/NU00283
Water