Heavy depth and shadows here, but might work well on some mobile apps.
Source Damian Rivas
Redrawn based on a drawing in 'По Сѣверо-Западу Россіи' Konstantin Sluchevsky, 1897.
Source Firkin
Looks like a technical drawing board: small squares forming a nice grid.
Source We Are Pixel8
Horizontal and vertical lines on a light gray background.
Source Adam Anlauf
Not so subtle. These tileable wood patterns are very useful.
Source Elemis
The unit cell for this seamless pattern can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
A heavy hitter at 400x400px, but lovely still.
Source Breezi
A seamless pattern based on a square tile that can be retrieved in Inkscape by selecting the rectangle and using shift-alt-i.
Source Firkin
A black tile-able background with paper-like texture.
Source V. Hartikainen
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Very dark pattern with some noise and 45-degree lines.
Source Stefan Aleksić
The image a seamless pattern derived from a weed which I can't identify.The original weed image is from here:https://jp.pinterest.com/pin/500744052301423641/
Source Yamachem
A textured blue background pattern with vertical stripes.
Source V. Hartikainen
This is a seamless pattern of regular hexagon which has a honeycomb structure.
Source Yamachem
Prismatic Geometric Pattern Background 2
Source GDJ
Brushed aluminum, in a bright gray version. Lovely 2X as well.
Source Andre Schouten
Zero CC tileable wood texture, made by me procedurally in Neo Texture Edit.
Source Sojan Janso
This seamless light brown background texture resembles a wallpaper with vertical stripes. One way to use it is as a tiled background on web sites.
Source V. Hartikainen
A pattern formed from repeated instances of corner decoration 8. To get the basic tile select the rectangle in Inkscape and use shift+alt+i
Source Firkin
The texture of this background image has some similarities with leather, and it's colored in a dark brown color. So, if you are looking for a dark brown background image for your website, this may be an option for you.
Source V. Hartikainen
A seamless pale yellow paper background with a pattern of animal tracks.
Source V. Hartikainen