for the spring equinox (and/or easter which is only a month later), i hid 40 plaster "eggs" in a walled-off section of forest for you to hunt down and collect! there are 30 large white eggs and 10 small brown eggs, all of which can be found without flying or digging or moving/removing anything. pick them up with a sledgehammer. see how fast you can find them all!
if you have a hard time, you can use the edit area tool in creative mode to turn plaster into luminous blocks (remember there are two different colors so you'll need to do it twice probably) to make the eggs stand out more.
this event comes in two versions. the blueprint version is just that- a blueprint of the event area, terrain and all, that you can place into your own world. the terrain has been mostly flattened and there is a sort of 'gateway' at the entrance so it should be easy to place, and the eggs are likely easier to find due to the flatter terrain. you'll need to bring your own sledgehammer tho, and signs don't hold text in blueprints so info is here not there. (note that i only placed the blueprint in the ocean to make sure it worked and get this picture, i didn't actually build the ground and place the plants/rocks, it's just cut from a part of my naturally-generated world)
the zip file version is an actual world/map that you will need to unzip/extract and load into, and has informational signs and tools/food provided for up to four players (tho the area may be a bit small for that many, do let me know). compete to find the most eggs in 30 minutes(or whatever time limit you choose)! note that the map has caves and animals turned off, as it is not meant for longterm play, but rather only for this event. the eggs may also be a bit smaller than the blueprint version, and the rugged terrain hides them better. so even if you are playing solo, you can go with this option if you just want more of a challenge.