The first up is The List of mythological objects this includes all kinds of things;"a variety of items (e.g. weapons, armour, clothing) found in mythology, legend, folklore and religion from across the world. This list will be organized according to the category of object"
Then there's the grand list from the 'List of mythological objects (Hindu Mythology)' this includes (e.g. weapons, armor, clothing). There's some awesome treasures and relics that relates to many of the sagas & stories. Perfect fodder for all kinds of adventures & OSR setting material.
Then there's the 'Thirteen Treasures of the Island of Britain list' which is includes;"The Thirteen Treasures of the Island of Britain (Welsh: Tri Thlws ar Ddeg Ynys Prydain) are a series of items in late medieval Welsh tradition. Lists of the items appear in texts dating to the 15th and 16th centuries. Most of the items are placed in the Hen Ogledd or "Old North", the Brittonic-speaking parts of what is now southern Scotland and Northern England; some early manuscripts refer to the whole list specifically as treasures "that were in the North". The number of treasures is always given as thirteen, but some later versions list different items, replacing or combining entries to maintain the number" These are perfect fodder material to slide your OSR adventurers into a Celtic or Authurian game setting or adventure with little issue. These can slide right into the Four Treasures of The Tuatha Dé Danann as a sacred side note to slip into place right inside a dark Europe adventure.
There's also a slew of relics, items, and artifacts from the Bible perfect fodder for adventures with a historical spin. The artifacts in biblical archaeology list is extensive and easily back fitted into the Relics associated with Jesus
entry which is perfect to spin all kinds of adventures around. This could include things like Nazi occult hunters, a bit of time travel, and spinning this stuff into adventures like the Lamentations of the Flame Princess dark historical setting or even as possible fodder for Eighties style horror with overtones of the Keep.
This makes back to back adventures a snap, Mayfair games did a 'Keep' adventure where you play adventurers in the past and their descendants in the future. Since then I've used this gimmick a few times and as long as the players are down with it. This seems to be a hit with some people who really enjoy this style of play.
I also came across this list of 10 Amazing Mythological Objects from listverse.
Remember to keep those dice rolling.