Heavy depth and shadows here, but might work well on some mobile apps.
Source Damian Rivas
Seamless pattern formed from a tile that can be had by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
Detailed but still subtle and quite original. Lovely gray shades.
Source Kim Ruddock
Not sure if this is related to the Nami you get in Google image search, but hey, it’s nice!
Source Dertig Media
Super subtle indeed, a medium gray pattern with tiny dots in a grid.
Source Designova
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
This was formed by distorting an image of a background on Pixabay.
Source Firkin
From an image on opengameart.org shared by rubberduck.
Source Firkin
Floral patterns might not be the hottest thing right now, but you never know when you need it!
Source Lauren
A pale orange background pattern with glossy groove stripes.
Source V. Hartikainen
Abstract Arbitrary Geometric Background derived from an image on Pixabay.
Source GDJ
Remixed from a raster on Pixabay, that was uploaded by ArtsyBee.
Source Firkin
A playful triangle pattern with different shades of gray.
Source Dimitrie Hoekstra
This is a grid, only it’s noisy. You know. Reminds you of those printed grids you draw on.
Source Vectorpile
Bright gray tones with a hint of some metal surface.
Source Hendrik Lammers
Background Wall, Art Abstract, Block Well & CC0 texture.
Source Ractapopulous
Dark blue concrete wall with some small dust spots.
Source Atle Mo
With a name like this, it has to be hot. Diagonal lines in light shades.
Source Isaac
A dark metallic background with a pattern of stamped dots. Here's a dark "metallic" background pattern for you.
Source V. Hartikainen
Heavily remixed from a drawing that was uploaded to Pixabay by ractapopulous
Source Firkin
Green Web Background, Seamless tile.
Source V. Hartikainen
A browner version of the original weathered fence texture.
Source Firkin
Recreated from a pattern found in 'Az Osztrák-Magyar Monarchia irásban és képben', 1882. To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Basket Fibers, Basket Texture, Braid Background style CC0 texture.
Source 1A-Photoshop