Honey I’m Subtle #1038
 Gray  CC BY-SA 3.0

A mid-gray hexagon pattern.

Source Alex M. Balling

 More Textures
Background pattern 242 (colour 6) #2199
 Pink  CC 0

Random colour tile.

Source Firkin

[email protected] #754
 Light  CC BY-SA 3.0

This is so subtle you need to bring your magnifier!

Source Carlos Valdez

Shapes pattern 2 (colour 3) #2239
 Blue  CC 0

A background made up of shapes.

Source Firkin

Subtle [email protected] #926
 Light  CC BY-SA 3.0

Super subtle indeed, a medium gray pattern with tiny dots in a grid.

Source Designova

Stone Granite #1292
 Stone  CC 0

ZeroCC tileabel stone granite texture, edited from pixabay. CC0

Source Sojan Janso

3D Wood #1475
 Wood  CC 0

Basket Fibers, Basket Texture, Braid Background style CC0 texture.

Source 1A-Photoshop

Brushed Aluminum 8 #1396
 Dark  CC 0

Gamedev - Metal Textures. CC0 License.

Source Davit Masia

Escheresque #777
 Light  CC BY-SA 3.0

Cubes as far as your eyes can see. You know, because they tile.

Source Jan Meeus

Background pattern #1941
 Brown  CC 0

Formed by heavily distorting part of a an image of a fish uploaded to Pixabay by GLady

Source Firkin

Wood Chips 3 #2101
 Unknow  CC 0

CC0 textures, backgrounds.

Source SliverKnight

Pixel bird pattern #1846
 Red  CC 0

Remixed from an SVG by Devanath found on Pixabay

Source Firkin

Plain & Wood #1356
 Wood  CC 0

CC0 for Free, hope you like it.

Source Yethiel

Background pattern 215 #2371
 Brown  CC 0

A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.

Source Firkin

Configurable Graph Paper #141
 Stripes  CC BY-SA 3.0

Pass parameters to the URL or edit the source code variables to configure the graph paper for the division desired.

Source JayNick

Checkered Light [email protected] #281
 Grid  CC BY-SA 3.0

Sort of like the Photoshop transparent background, but better!

Source Alex Parker

Floral background 21 #1785
 Dark  CC 0

From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.

Source Firkin

Autumn leaves pattern #2468
 Brown  CC 0

A seamless pattern formed from leaves.

Source Firkin

Micro Carbon #7
 Carbon  CC BY-SA 3.0

Three shades of gray makes this pattern look like a small carbon fiber surface. Great readability even for small fonts.

Source Atle Mo

Ribbon pattern 2 (version 2, colour 4) #2036
 Colorful  CC 0

The tile this is based on can be retrieved by selecting the rectangle in Inkscape and using shift+alt+i.

Source Firkin

Textured [email protected] #868
 Stripes  CC BY-SA 3.0

A lovely light gray pattern with stripes and a dash of noise.

Source V. Hartikainen

"Beige Wall", Tileable Background #1189
 Concrete  CC BY-SA 3.0

This beige background pattern resembles a concrete wall with engravings or something similar to it.

Source V. Hartikainen

[email protected] #830
 Dark  CC BY-SA 3.0

Not the Rebel alliance, but a dark textured pattern.

Source Hendrik Lammers

Starry Star #1918
 Dark  CC 0

Fix side and a seamless starry tile.

Source SliverKnight

White Wave #681
 Stripes  CC BY-SA 3.0

Light and tiny, just the way you like it.

Source Rohit Arun Rao

Tileable [email protected] #656
 Wood  CC BY-SA 3.0

Not so subtle. These tileable wood patterns are very useful.

Source Elemis

Tall plant #1818
 Dark  CC 0

From a drawing in 'The Christian Year', John Keble, 1880

Source Firkin

Prismatic Dots Background [email protected] #516
 Noise  CC 0

Prismatic Dots Background 8

Source GDJ

Background pattern 224 (colour 3) #2340
 Colorful  CC 0

To get the tile this is based on, select the rectangle in Inkscape and use shift-alt-i.

Source Firkin