I'm floored by how well-thought-out (and benevolent!) this answer is. You certainly don't take cause and effect lightly. Not only would the progression in society be jolting, but I'm sure there would be millions of pilgrimages made and, frankly, I could even foresee a war erupting over it at some point if the conditions were right.
The only thing is now that you've firmly talked yourself out of it, you're back at square one! Better pick again.
Well I would start with the most impressive artifact of all: The adventurer's baggage... What, you never heard of it? It's the invisible yet dimension holding bag that heroes have passed on since the Merethic age. You know; the invisible backpack that holds all your items and random crap. Then before I leave Nirn I would just stuff it with all kinds of stuff.
If that's considered cheating I would bring a sappling or a seed of a Hist. In my field of study (I'm a student in plant biology) it would be a huge breakthrough to discover a sentient tree, I would plant the thing in my garden, get a nobel prize before I turn 25 and be generally awesome, also I would start breeding argonians for the fun of it.
Or perhaps a phial of werwolf blood, I would roam the lands (or towns, cities, parcs...) at night, eating wildlife (or sheep, cows, cats...). It would be awesome, I would definitively go eat a few old teachers or something... Oh well I'll figure it out.
However if I were to choose two items (the last two above) I would plant the hist tree, get some sap, buy a pet lizard and feed it to him until he turns into an argonian, give him the werewolf blood and call him Sotek, just for giggles.
2000 of each race on Tamriel, for pure fun. Just image what would happen if 2000 Orsimer appeared in the middle of London. If this is not allowed then perhaps Auriel's Bow and a supply of blood cursed and sunhallowed arrows so I can set myself up as a leader of a sun worshiping cult or something like that, or just have fun playing around with the sun and confusing scientists.
I would love to get a full set of the Nightingale Armor! It's my favorite armor from the game, and happens to look great on both male and female characters. :) Otherwise I think I'd like a good stock of high quality healing potions. Never know when they'd come in handy or who might need one!