I have recently acquired a complete set of Harvard Classics. They're royal blue with silver lettering. The only date that I can find in them is 1909, so that's when I'm assuming they were published. They are edited by Charles W. Eliot , LL.D. by P. F. Collier and Son Corporation. The man I bought them from told me they were somewhat of a collector's edition... but who knows. Any help about these books would be appreciated, even about what the different colors of the different sets mean (some are read/green/white etc.).
Thanks!

Call the reference desk at your local public library. They will get information for you as to colors, price, collectibility, etc. The set is basically antique status now that's it's about 100 years old.

Thanks for your help! I did that and I found out a lot about those books and others I have as well.

HI, P.F. or Peter Fenelon Collier was an Irish immigrant to the U.S. and the Harvard Classics among many other inexpensive book sets he published were the forrunners of book of the month clubs. You bought a subscription for monthly books. At one time these were advertised as "The Five Foot Shelf of Books". A good place for you to look would be abebooks.com where there are literally hundreds of these volumes for sale at a dollar and up.