Heavy depth and shadows here, but might work well on some mobile apps.
Source Damian Rivas
Prismatic Groovy Concentric Background 5
Source GDJ
All good things come in threes, so I give you the third in my little concrete wall series.
Source Atle Mo
Zero CC bark from fur tree tileable texture, photographed and made by me. CC0
Source Sojan Janso
As far as fabric patterns goes, this is quite crisp.
Source Heliodor Jalba
Green Background Pattern
Source V. Hartikainen
Prismatic Isometric Cube Extra Pattern No Background
Source GDJ
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Remixed from a drawing in 'A Girl in Ten Thousand', Elizabeth Meade, 1896.
Source Firkin
The edges of all the red objects line up either vertically or horizontally, but it doesn't appear so. Made from a square tile that can be got by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Sharp diamond pattern. A small 24x18px tile.
Source Tom Neal
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
A background pattern inspired by designs seen in 'Burghley. The Life of William Cecil', William Charlton, 1857.
Source Firkin
Can never have too many knitting patterns, especially as nice as this.
Source Victoria Spahn
Number 2 in a series of 5 beautiful patterns. Can be found in colors on the submitter’s website.
Source Janos Koos
Hexagonal dark 3D pattern. What more can you ask for?
Source Norbert Levajsics
Light gray grunge wall with a nice texture overlay.
Source Adam Anlauf
Greyscale version of a pattern that came out of playing with the 'light rays' plug-in for Paint.net
Source Firkin
Vertical lines with a bumpy, yet crisp, feel to it.
Source Raasa
This is a semi-dark pattern, sort of linen-y.
Source Sagive SEO
Luxurious looking pattern (for a T-shirt maybe?) with a hint of green.
Source Simon Meek