According to my calendar, tomorrow is the date of the Lesser Mysteries this year. I was going to write up something up about them, but when I went to gather my resources, I found that Baring the Aegis has already done the work for me. Bless them! 

So here, have some links: 
The Eleusinian Mysteries

The Lesser Mysteries

Seriously, check out the articles that are tagged over there for the Mysteries. It’s a treasure.