New Rare Items Theory

I picked up a sunstone from a regular spin today. It took 400+ spins to get one though for me. I also received an item from my 7 day spin a few days back which seems to be a high drop rate for these items.

got sun stone from a regular spin. probably after 60-70 spins since the update

I got a metalcoat on a regular spin. The upgrade is from my 7 day streak.
So you have a small change on regular spins 2 ?

I got an Upgrade from a regular spin.

Preliminary reports seem to suggest that you are guaranteed, or at least a significantly higher chance, one evolution item with you 7th day streak. I got my first and only evolution item so far from my 7th day streak. This doesn't rule out a rare chance at getting one from a normal spin though.

I got 2 dragon scales from regular spins and a metal coat from the 7 day spin.

My only item so far has been a sun stone from my 7th day spinning.

Same as others. I got one as part of my 7 day streak. Haven't seen one otherwise.

Early esimates are 1/2000 (.05%) chance for evolution item in a regular spin, it'll take a pretty sizable data set to get a conclusive number.

I got an upgrade from the 7th day spin, another Upgrade and two Sun Stones from regular spins.

I got my one item on a first spin of the day bonus, but it wasn't the 7th day. I think it was 4th day...

4 total items so far, none from a daily streak. I guess I've been RNG lucky...

A lot of people have had an ítem from their 7 day strike. After +300 pokestops without any ítem I got 2 in my 7ds.
Also I got another one today from a regular spin.

Yes, I got 2 metal coats from normal spins the first day after gen2 was released. I spun less than 15 pokestops for that. My next item came from a 7th day spin.

Yep, got a random metal coat yesterday. I think it's just they appear as a small % of the number of items, so on 7 day spins you just get so many items that you're most likely to get one then.