Chicory can refer to either the green leaves or the fibrous roots of the plant. Both are Paleo-friendly, although they have different benefits.
The leaves are an excellent source of vitamins A, K, and various B vitamins, with vitamin C making a respectable showing as well. You can throw these babies in salads or stir-fry them for a few minutes to soften them up. Wherever you would normally use leafy greens, you can use chicory leaves.
The roots have only moderate amounts of vitamins and minerals, but they are extremely rich in fiber in the form of inulin. This stuff is a potent prebiotic that has been shown to positively affect gut flora, counteract constipation in the elderly, and increase flatulence in healthy men. If it causes discomfort, you may want to lower the dosage.
Mark gave chicory is Primal seal of approval.