Funny you should post this. I have been really impressed by the 'seaside mallow' Kosteletskya virginica . It was from seed I picked from a plant by the bridge down the road. I had dozens of little plants. Most went to my daughter's since pink is her favorite color. Several grew beautifully in a big pot I kept here. I have just recieved a white one from a southern nursery.
I also grew garden varieties of what I am going to call the common Marsh Mallow. They grew 5 feet tall with flowers the size of dinner plates, but the smaller pink or white ones are one of the commonest plants in the wild here. They will grow on higher ground but are native to the marsh edges. I still have them after 20 years.
Smartweeds are indeed weeds but they cover large areas of the local wildlife refuge pool edges and are pink. I cannot say they would thrive with tidal changes.
Down the road the marsh is filled with cardinal flowers every fall. I am sure I will think of others. Get a book about wildflowers and check out the ones that grow in marshes and swamps. There is an amazing selection, but only a few tolerate salt water 2x a day.

You could check with your local extension office for a list of plants that will do well in your location. You want to be sure that whatever you plant is not an invasive that will cause further damage to the delicate environment of the Bay. Also, the Chesapeake Bay Foundation may have recommendations.

G'Day!
- Sounds as if you want to search for "native flowering marsh plants." And Sandy's suggestions, above, are exactly where i would start.

- For somre reason, marshes seem especially suseptable to invasives.

- Don't know if our native blue flag iris would work for you; you mention tides, but in the Bay that may or may not mean salt or brackish water.

- Maybe search seaside plants as well?

- Sea grapes don't bloom in a showy manner but they are neat plants.

- Happy gardening,
-vlad

Try these folks- I bet they'll be more than glad to help

Here is a link that might be useful: VA Native Plant Society