A very short search through anything related with the FAA (let alone wikipedia page on the subject) will show that just about every aircraft shown has roundels. Wiki describes them as the insignia of the service. Every Stringbag you've ever seen carries them, as does almost every Seajet, and everything else in between. Why/how does this come as a surprise? Virtually every aircraft the FAA ever had wore them.
ps. Google is crap. Use webferret instead.