How did it get there?

[abn21]

I found a uniform button at an old confederate earth works site off of I-95 near Beaufort, SC. The button was about 20mm with the letters LA written in script in the middle, a #1 under the "LA", surrounded with 16 five pointed stars. After looking on the internet....as far as I can tell, it's from the 1st Regiment, U.S. Light Artillery (1808-1821)
I didn't think the War of 18 12 was fought in this area. What are your thoughts on how it got there.