Anywhere from Sea Rim State Park 10 miles west of Sabine Pass, down the coast to High Island, to Gilchrist (Rollover Pass), to Crystal Beach, to Galveston is good.
If you go to the Boat Launch at Dick Dowling Park, launch, and travel north a short ways, pass a small canal, beach the boat and hunt the muddy bank (Tx side) of the Sabine Ship Channel,
there are Spanish artifacts and Civil War items too. The old Lighthouse on the La. side had fighting there too.
Sabine Pass was about 14,000 during that War, and today its a few hundred. Six miles west of Sabine is Ft Manhassett,
a Confederate fortification of 5 redoubts.
(I can put you on some good salt water fishing too.) I was born in Beaumont and (grew up in Jacksonville) and moved back to Beaumont after the Army.
Spindletop Oil Field (Town) near Lamar is a good site too.
If you go to Galveston be sure to go by Jean Lafitte's old house site too. (I know some of his kin folk in Lake Charles.)
What detectors do you use? Some of the ground in areas is mineralized.