I keep track of the Official LOTRO Schedule maintained by the Community Manager, Cordovan, and edit my Google Calendar embedded below to show the same data in a different way.
Note: unless it says otherwise, all events will start at 10 AM and end at 3 AM (server time/EST).
Below (and in this link) you can see the events planned until the end of the year. There’s only one event “observed” because the date in the Official source for this calendar seems wrong (a Crafting XP event has never lasted near 20 days – so that’ll need correcting).
Pinned: Official Event Schedule (Forum Thread)