Ivy Style (the fashion) is historical, in my view the most enduring genre of fashion in American history.
Ivy-Style.com (the site) is probably the richest source of reference and information on that history. Images, essays, all of it. There is well over a decade here of research and writings. The site is an exhaustive cataloging of the style.
They say that those who ignore history are doomed to repeat it. In this case, I am not so sure that is a bad thing. Still, for inspiration, spend some time here.
As the site moves forward, it is really fun, and inspirational, to look backward.