Mussels aren't found in our waters. WF has them for a reasonable price. I really like them at Irene's and Cafe Grenada (in a nice, spicier than you'd expect red sauce). Tommy's are similar to Irene's but IMO don't taste as good. Not impressed with Rio Mar's. Lilette's are good, not great. Bistro at Maison De Ville's are merely ok, topped with frites and a gob of aioli. Lola's has them marinated and cold, also not a favorite. They are a breeze to prepare at home and will likely be much better than what the rest. are serving.
I've had fresh water mussels from some of the oxbow lakes, like Lake St John and Concordia. They left a lot to be desired, though the prep could well be suspect.
If one is looking for salt water mussels, I think that all, that are good, will be imported from the Atlantic.
However, I could be wrong. Not THAT long ago, I had Mississippi stone crab, that was great. I had caught one, as a child in Bay [of] St Louis, but never thought of them as being something that was likely to be found in any quantity in the Gulf. Ya' grow up, and fish the waters for much of your life, and then learn something later on. To me, they were not likely to be found out of FL waters. As Rod Stewart sang, "look how wrong you can be... "