There are 3 nameless treasures that you can find in Liyue region, and you can find them in Dunyu Ruins, Lingju Pass, and Qingxu Pool. They aren't part of an official quest, by getting all 3 can be exchanged for 100,000 Mora.
Dunyu Ruin Puzzle
How to Lower the Water Level
You can start by going to the Geo pillar in the ruins. To unlock the seal, you'll need to light 4 candlesticks in the area.
The first 2 is close to the Geo pillar shown in the picture above. 1 next to it, and the other on top of the pillar on the side.
The other 2 is just 1 level below the Geo pillar. 1 at the edge of the broken bridge, and the other is further inside the middle level. After you light all 4, activate the Geo pillar using a Geo elemental attack and it will lower the water level. Once you lower the water levels, I suggest that you change to your battle party since there's going to be a lot of fighting
You will then need to guide 3 seelies to the sealed chest in the middle. Start with the one close to the Geo pillar, and guide it down to the lowest level. The other 2 remaining seelies are on the opposite ends of the lowest level.
Climb up the using the corner area there, and go inside through the upper window. Clear out the enemies and guide the seelie to the center.
The last seelie is blocked by a golem. Simply defeat it and go inside to guide it to the sealed chest. Once you are done with all 3, simply pick up the chest to get 1 of the nameless treasures.
The other nameless treasure is in Lingju Pass. To get this, you'll need to complete the "And This Treasure Goes To..." quest.
Last location is at Qingxu Pool, and you'll need a Geo element character for this as well. You can use the main character and change their element to Geo by interacting with any of the "Statue of The Seven - Geo" and resonate with it. Ningguang will also work if you happen to have her from the gacha.
You can reach there pretty easily by gliding down to the area from the teleport waypoint, located just below the ruins on the map.
Feel free to explore the area first, since there are a lot of treasures. But if you want to get the last nameless treasure, go to the upper area near the front of the ruins. Start by interacting with the stone tablet, and activate the Geo seal that's right in front of it.
You'll need to activate 4 more Geo seals, and they are all in the pavilions around the stone tablet. Two of them are in front of the stone tablet.
The other two are behind the stone tablet. Once you are done with the 5 seals, head back to the stone tablet and open the treasure.
Exchanging the Nameless Treasures
To exchange the nameless treasures, you'll need to go to Liyue city and go to the npc that's right next to Mingxing Jewelry (the diamond icon shown on the map), next to the stairs.
This npc will only show up past 21:00. Use the "time" feature to change the in-game time if it's not past 21:00 yet. The "time" feature is below the mail icon when you press the main menu on the very left. If the npc doesn't show up, then try teleporting to the city again or log out and back in again.
Once you're there, talk to her about the nameless treasures and she will offer you 100,000 Mora for it. There are no other known ways to use the nameless treasures.