The Church Music Association of America website (musicasacra.com) has a wealth of information for priests and lay people on the use of chant and polyphony in the Mass.
They publish the Sacred Music magazine, which is edited by Prof. William Mahrt from Stanford.
And they have a huge number of books in PDF format for download, including books on how to sing Gregorian chant, music, and such treasures as the Liber Usualis, which identifies which chants should be sung on which days.
And they have a yearly colloquium.
CMAA Colloquium Gets You in Touch with Like-Minded People
I have attended two CMAA colloquiums, and I can't say enough good about the experience. At the colloquium, we practiced chant and polyphony and sang it at daily Masses, some in the Novus Ordo and some in the Usus Antiquor, and always in Latin after the first Mass. Sing to the Lord morning, noon, and night for 7 days, that is my idea of a good time!
Two photo albums I created for the CMAA are here:
At the colloquium, I met a lot of zealous young people from as far away as Singapore who are "trads." The link above shows a young woman who came the colloquium from Singapore. She refers to herself and her friends as Liturgy Loonies.