Because I randomly started writing it, here is something about fairy holidays I wrote up:
Fairies very rarely work or have that much real religious reverence (many fairies are religious in some sense, but tend to treat it more like informal fanclub then organized institutions, in fact many fairies would count human fandoms as a type of religion), but none the less often enjoy having the excuse to party or indulge more then normal. There are eight major holidays and many more minor ones. The eight major ones include the two solstices, the two equinoxes, and four seasonal transitions. It also should be noted that lots of fairies don't always agree on what to celebrate on these days or what they should be called, but most of them generally feel there should be some kind of special event on these days. There are some genuinely accepted versions of the eight holidays.
The first and most important is the winter solstice, which starts the 12-ish day festival known as Yuletide. This festival also marks the end of the year and the start of a new one. Often it is celebrated in ways that are similar but distinct from the human celebration of Christmas which is it's Christianized counterpart. In particular decorating trees, giving gifts, singing, burning a yule log, and eating feasts of ham are all traditional Yuletide traditions. The day of the solstice is often called Yule and can be a time where friends gather to share a meal and give gifts. The night before often starts the celebration with The Festival of Stars where fairies will often stay up and stargaze with friends. Near the end, on what is our new year's eve, there is what we call The Festival of Lights where we use magic and fireworks to put on a show. It's also the time of year when the Wild Hunt takes place, a tradition started by Odin in the form of the Yule Father who is kind of our version of Santa Claus. During the hunt we traditionally hunt and kill a wild boar for our feasts, though the hunters don't always hunt boars or kill their prey. After the hunt comes the Yuletide feasts which can continue into next morning. There are often lots of fun activities that change from year to year, but those are the big ones.
Our next major holiday is Cleansing Day which is the traditional first day of spring midway between the winter solstice and spring equinox. It is similar in ways to Imbolc. It is celebrated manly by doing some spring cleaning, bathing in special springs, and lighting candles in the evening. It is often a day for coming together to overcome old grudges and has also acquired some traditions similar to Valentine's Day as a day for lovers to get together and spiritually cleanse themselves with each other's love. Though since fairies are not exclusively monogamist or always have a clearly defined separation between 'friend' and 'lover' this is can be a bit chaotic.
After that, on the spring equinox we celebrate Laying Day. It is often celebrated with traditions that vaguely resemble some of the more non-Christian elements of Easter, namely the symbology of rabbits and a tradition of hiding eggs. Though rather then a rabbit hiding chicken eggs, fairies lay and hide their own eggs. Since they are immortal fairies cannot have children, but their eggs still serve an important function. When a fairy is 'killed' their spirit returns to an egg which hatches into a new body. Though there are large public stashes of eggs, many fairies like to keep their own secret stashes close by so they don't have to travel as far. Laying Day is a great way to get fairies to remember to check on their stashes and to gather egg collections for the public ones. Plus it's lots of fun! In order to lay lots of eggs we have to... well I am sure you know why rabbits are such a great symbol.
Next is May Day, celebrated on what is traditionally the first day of summer between the spring equinox and the summer solstice, which is one of the few holidays that humans and fairies both celebrate in a lot of the same ways. A lot of the dancing around the maypoll, the Morris Dance, the choosing of a May Queen. A May Queen of the celebration is often traditionally a human who has been chosen to become a fairy. Because fairies cannot have children normally we often adopt humans we like and turn them into fairies. The gender of the human doesn't matter, most May Queens end up as female fairies anyway. The Morris Dance is a very important tradition to welcome the summer.
Next we have Midsummer on the summer solstice. On this day we often light bonfires and just kinda have a fun festival. It's kinda much more of a loose thing, with lots of different food, games, music, and dancing that mixes lots of different traditions and styles. It's not that different from a lot of the summer festivals humans throw to be honest. One interesting thing is that while fairies tend to hate crowds and on other holidays we all tend to celebrate in smaller groups (even the Wind Hunt tends to be done with smallish hunting groups outside of one or two big ones), this day is the most likely that lots and lots of fairies will try and meet up in massive fairs with big crowds.
Next is Lammas, the traditional first day of fall and midway between the summer solstice and the fall Equinox. Often called or associated with Lughnasadh. It is celebrated most often with feasts primarily of bread and honey served with berries and fruits. It marks the start of the 'harvest season'. Fairies are not agricultural in the traditional sense in that they create and grow most of their food with magic, or by hunting and gathering in their magically rich world. Even so we still do venerate the cycles of nature and the harvest.
Next is Harvestfest which is celebrated on the fall equinox. We often celebrate with a big feast of some kind. American-style turkey dinners have actually become a popular choice since fairies started paying attention to human culture. It is also partly related to various Thanksgiving traditions though it descending from older harvest festivals, but in general fairies do not show public displays of gratitude unless they need to. Private shows of thankfulness to the earth or others isn't uncommon on this day though. It's the one day out of the year that some fairies show their gratitude.
Last of the eight but not least is Samhain which is celebrated on the traditional first day of winter midway between the fall equinox and the winter solstice. Known to by it's Christian name as Halloween, this is the day where the gap between worlds is smallest, and fairies often come to the human world to play pranks or trick-or-treat in for candy. Often both. It's a time when many creatures from lots of different worlds can meet up and play in the human world. We can all go out in public and the silly humans don't suspect a thing! It's also the time to preform what is know as the Dark Morris to welcome the winter. It is preformed like the Morris Dance on May Day only in secret and in silence, without spectators or music.
There are other minor holidays that are often observed. One is Trickster's Day. It is often equated to what humans call April Fools, and it also honors the great tricksters of lore (such as Loki, Eris, The Coyote, Kitsune, Tanuki, even Bugs Bunny). Another is Witch's Night which is often celebrated on the eve before May Day. It is a night in remembrance and appreciation for human magic users who used to be so friendly with fairies and other supernatural beings, and a night of showing off magical skill. Trying to list them all might be impossible. Fairies tend to celebrate anything they feel is worth celebrating anyway, and can just make up holidays on the spot sometimes too. They love holidays like International Talk Like a Pirate Day. Having some sort of special day is always fun, but a lot of them can become popular and then fade and vanish pretty quickly.
So there you go! I hope that educated you about fairy culture!