Owen Jones classic The Grammar of Ornament is online. The 1910 edition is provided free by the Digital Library for the Decorative Arts and Material Culture
Another gem from the same collection of e books also by Owen Jones is the 1867 edition of Examples of Chinese ornament selected from objects in the South Kensington Museum and other collections. Page after page is houses enough design inspiration to keep you busy for the next year.
I warn you need a couple of hours on this site to browse and discover what is on offer.