I take an iodine supplement and use Himalayan Pink Salt. I've never seen a natural salt with iodine (not to say it doesn't exist).
This is what Dr. Michael R. Eades has to say about it:
In addition to broth, get some Celtic Sea Salt, Himalayan Salt or one of the other grayish, pinkish kind of grungy looking salts and replace your normal salt with these. And don’t use them sparingly. These salts have been harvested either from ancient sea beds or obtained by evaporation of sea water with high mineral content and contain about 70 percent of the sodium of regular salt (which has been refined, bleached and processed until it is pretty much pure sodium chloride, often with anti-caking agents added). The other 30 percent of the volume is other minerals and micronutrients (including iodine) found in mineral-rich seas. Consuming these salts is not just following a Paleolithic diet using modern food, but, depending upon the origin of the salt, it is consuming the same food your Paleolithic ancestors ate. I much prefer these salts taste-wise to regular salt, and I salt the heck out of all my food with it.
Tips & tricks for starting (or restarting) low-carb Pt II » The Blog of Michael R. Eades, M.D.