Sometimes simple really is what you need, and this could fit you well.
Source Factorio.us Collective
ZeroCC tileabel stone granite texture, edited from pixabay. CC0
Source Sojan Janso
A seamlessly tileable pink background texture.
Source V. Hartikainen
Used in small doses, this could be a nice subtle pattern. Used on a large surface, it’s dirty!
Source Paul Reulat
Looks as if it's spray painted on the wall. You can be sure that this pattern will seamlessly fill your backgrounds on web pages.
Source V. Hartikainen
Like the name says, light and gray, with some small dots and circles.
Source Brenda Lay
A seamless pattern formed from a sports car on clker.com. To get the tile, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
First pattern tailor-made for Retina, with many more to come. All the old ones are upscaled, in case you want to re-download.
Source Atle Mo
From a drawing in 'Two Women in the Klondike', Mary Hitchcock, 1899.
Source Firkin
Formed from a tile based on a drawing from 'Viaggi d'un artista nell'America Meridionale', Guido Boggiani, 1895.
Source Firkin
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Otis Ray Redding was an American soul singer-songwriter, record producer, arranger, and talent scout. So you know.
Source Thomas Myrman
I’m not going to use the word Retina for all the new patterns, but it just felt right for this one. Huge wood pattern for ya’ll.
Source Atle Mo
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
A textured blue background pattern with vertical stripes.
Source V. Hartikainen
From a drawing in 'At home', J. Sowerby, J. Crane and T. Frederick, 1881.
Source Firkin
There are many carbon patterns, but this one is tiny.
Source Designova
Alternative colour scheme for the original floral pattern.
Source Firkin
Utilising some flowers from Almeidah. To get the unit tile, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
From a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin