Yes sir, you found a pair of lapel pins from a relatively modern (1930s-1950) army dress uniform.
The US Disc is worn on the opposite lapel as the branch insignia disc, yours belonging to a GI that served in the Coastal Artillery Corps.
The Coast Artillery Corps was realigned with Field Artillery and ultimately disbanded in 1950, after the threat of imminent attack by Japan/Germany subsided.
If it has to be a "modern" military find on US soil, you found a real keeper.