Congruent Pentagon #1307
 Unknow  CC BY-SA 3.0

Inspired by this, I came up with this pattern. Madness!

Source Atle Mo

 More Textures
Light Sketch #669
 Paper  CC BY-SA 3.0

Nice and gray, just the way I like it.

Source Dan Kruse

Prismatic Groovy Concentric Background 5 #465
 Dark  CC 0

Prismatic Groovy Concentric Background 5

Source GDJ

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

Tileable Off-white Background #1191
 Concrete  CC BY-SA 3.0

A free tileable background colored in off-white (antique white) color.

Source V. Hartikainen

Floral background 5 #2404
 Fabric  CC 0

A seamless pattern formed from a square tile. The tile can be retrieved by selecting the rectangle in Inkscape and using shift-alt-I.

Source Firkin

Background pattern 8 (colour) #211
 Noise  CC 0

Colour version of a pattern that came out of playing with the 'light rays' plug-in for Paint.net

Source Firkin

Background pattern 329 #1769
 Dark  CC 0

A pattern formed entirely from squares

Source Firkin

Paper [email protected] #1061
 Paper  CC BY-SA 3.0

Just what the name says, paper fibers. Always good to have.

Source Heliodor jalba

Floral pattern 17 (colour) #1724
 Orange  CC 0

Derived from an image that was uploaded to Pixabay by mdmelo.

Source Firkin

Reticular Tissue #763
 Light  CC BY-SA 3.0

The act or state of corrugating or of being corrugated, a wrinkle; fold; furrow; ridge.

Source Anna Litvinuk

[email protected] #1141
 Gray  CC BY-SA 3.0

The classic subtle pattern. Sort of wall/brick looking. Or moon-looking?

Source Joel Klein

Prismatic Abstract Geometric Background 4 No [email protected] #443
 Dark  CC 0

Prismatic Abstract Geometric Background 4

Source GDJ

Part of Bayeux Tapestry 4 #2446
 Noise  CC 0

From a drawing in 'Les Chroniqueurs de l'Histoire de France depuis les origines jusqu'au XVIe siècle', Henriette Witt, 1884.

Source Firkin

Wavy background #2022
 Blue  CC 0

CC0 and a seamless pattern from a tile drawn in Paint.net .

Source SliverKnight

Black Wall #1267
 Wall  CC 0

Zero CC asphalt, pavement, texture, photographed and made by me. CC0 WARNING I FOUND A SEAM ON THIS TEXTURE

Source Sojan Janso

"Dark Brick Wall", Background Pattern #1024
 Stone  CC BY-SA 3.0

Like the name suggests, this background image consists of a pattern of dark bricks. It may be an option for you, if you are looking for something that looks like a brick wall for use as a background on web pages. It's not a masterpiece, but looks pretty nice when is tiled.

Source V. Hartikainen

Kaleidoscope Prismatic Abstract No [email protected] #807
 Noise  CC 0

Kaleidoscope Prismatic Abstract No Background

Source GDJ

Background pattern 240 #2209
 Dark  CC 0

Remixed from a drawing in 'A Girl in Ten Thousand', Elizabeth Meade, 1896.

Source Firkin

Decorative divider #2001
 Dark  CC 0

From a drawing in 'La Principauté de Liège et les Pays-Bas au XVIe siècle', Société des Bibliophiles Liégeois ,1887.

Source Firkin

Vintage pattern #1959
 Grid  CC 0

Formed from a tile based on a drawing from 'Viaggi d'un artista nell'America Meridionale', Guido Boggiani, 1895.

Source Firkin

Prismatic Hypnotic Pattern No [email protected] #572
 Noise  CC 0

Prismatic Hypnotic Pattern No Background

Source GDJ

Dark [email protected] #620
 Dark  CC BY-SA 3.0

Continuing the geometric trend, here is one more.

Source Mike Warner

Page ornament 29 #2307
 Red  CC 0

From a drawing in 'Az Osztrák-Magyar Monarchia irásban és képben', 1885.

Source Firkin

Norwegian Rose #857
 Light  CC BY-SA 3.0

I’m not going to lie – if you submit something with the words Norwegian and Rose in it, it’s likely I’ll publish it.

Source Fredrik Scheide

Background pattern 250 (colour 3) #2169
 Colorful  CC 0

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

Source Firkin

Background pattern 312 (colour 2) #1859
 Red  CC 0

Alternative colour scheme

Source Firkin

Subtle White Feathers #1103
 Light  CC BY-SA 3.0

This one is amazing, truly original. Go use it!

Source Viahorizon

Grid Paper Background (Blue Gray) #1162
 Grid  CC BY-SA 3.0

A free grid paper background pattern for using on web sites.

Source V. Hartikainen