Stat boosting Items I've seen so Far

[Vash The Stampede]

The headband that sets int to 17. Pretty sure most who played EA know of this
Clothing/Armor (AC10) Has +2 Dex to a max of 20 (haven't tried but I doubt this stacks with the next item)
Gloves - Sets Dex to 18 - Want to go tavern Brawler monk and still have decent Ac, now you can simply dump Dex and put these on. Good for Barbs also.
Clothing/Armor (AC10) +2 Str to a max of 20
That is all I've found so far. If anyone else found others feel free to post them.

[ChrisProtagonist]

Club of hill giant strength increases str to 15

[Gewinnste]

ChrisProtagonist a écrit :

Club of hill giant strength increases str to 15

To 19, not 15 ! You can equip it to your off-hand and it still gives you 19 strength!

[Kemaro Kitsune]

Dammon when found in Last Light Inn sells you a Blue quality item called "Harmonium Halberd" a +1 weapon that also gives you a +2 to strength and it also allows you to break the Str cap to a maximum of 23.

By using this weapon with the Mighty Cloth and Auntie Ethel's Boon to strength i'm sitting pretty at 22 str with no ASIs. Awesome item combo for a strength based character.

The halberd does reduce your wisdom and intelligence by 1 tho. Best weapon for a himbo i suppose, Which fit my barbarian perfectly lol

[Gewinnste]

I assume you already know Auntie Ethel's Hair (Act 1)? You can choose which ability you want +1 permanently and if you later up-level this stat to 20, I'm pretty sure this will get it to 21, i.e. the hair will be applied AFTER your up-leveling.