Our area is known for having great local clams. You can find them along the sandy banks of most of the waterways and creeks of the lower Cape Fear.
Clams, along with Oysters, are Bivalves.  They are filter feeders, meaning they constantly circulate water in and out of their bodies to strain out microscopic food. 
Although clams can move a little they generally spend their entire life in the same spot. The average life of a clam is 5-6 years but can live up to 35 years.  
You can collect clams year round. All you need is a garden rake or you can dig around with your toes. Find a sandy tidal area that is below the mean low water line and pull the rake through the sand until you feel it scratch a hard surface. Then, using your hands, excavate around that area to find your clam. Keep then cold until you are ready to cook them. You should not keep them longer than 2-3 days.
Remember: Clams must be 1” thick to keep. You may keep up to 100 per person per day, but not more than 200 total on your boat regardless of the number of people onboard.