Stone Wall & Dark #1523
 Stone  CC 0

Incoming catena. Stone & well. CC0 texture.

Source Unknow

 More Textures
Retro Circles Background 7 #431
 Unknow  CC 0

Retro Circles Background 7

Source GDJ

Congruent Pentagon #1307
 Unknow  CC BY-SA 3.0

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

Source Atle Mo

Background pattern 230 (colour 2) #2302
 Green  CC 0

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

Source Firkin

Black And White Floral Pattern Background Inverse #197
 Dark  CC 0

Black And White Floral Pattern Background from PDP.

Source GDJ

Diamond pattern 2 (colour 3) #2266
 Colorful  CC 0

From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.

Source Firkin

Sewn Stripes Pattern #964
 Stripes  CC BY-SA 3.0

A seamless pattern of "sewn stripes" colored in light gray.

Source V. Hartikainen

Square frame 3 #2354
 Dark  CC 0

Formed in Paint.net and vectorised in Vector Magic.

Source Firkin

Tree and bird pattern #1982
 Green  CC 0

From a drawing in 'Line and form', Walter Crane, 1914.

Source Firkin

Wild [email protected] #989
 Dark  CC BY-SA 3.0

Wild Oliva or Oliva Wilde? Darker than the others, sort of a medium dark pattern.

Source Badhon Ebrahim

Metal Pole Rusty & Glod #1654
 Metal  CC 0

Metal-Rusty. CC0 License.

Source Unknow

Abstract Ellipses Background Grayscale #814
 Dark  CC 0

Abstract Ellipses Background Grayscale

Source GDJ

Stone Wall & Yellow #1552
 Stone  CC 0

Incoming catena. Stone & well. CC0 texture.

Source Unknow

Leafy pattern 8 #1806
 Dark  CC 0

Inspired by a JPG that was uploaded to Pixabay by kokon_art

Source Firkin

Repeating Wood Straw Background #887
 Wood  CC BY-SA 3.0

A repeating background with wood/straw like texture.

Source V. Hartikainen

Dark Stripes #39
 Dark  CC BY-SA 3.0

Very dark pattern with some noise and 45-degree lines.

Source Stefan Aleksić

Seamless Colorful Floral Pattern Background #256
 Fabric  CC 0

PDP

Source GDJ

Vintage Clay Tile 5 #1462
 Unknow  CC 0

Gamedev - Roofs Textures. CC0 License.

Source Davit Masia

Transparent Square Tiles #298
 Grid  CC BY-SA 3.0

The first pattern on here using opacity. Try it on a site with a colored background, or even using mixed colors.

Source Nathan Spady

Brick pattern #2424
 Wall  CC 0

A simple rendering of a brick wall.

Source Firkin

Abstract Stars Geometric Pattern Prismatic No Background #384
 Noise  CC 0

Abstract Stars Geometric Pattern Prismatic No Background

Source GDJ

Stone Wall & Dark #1548
 Stone  CC 0

Incoming catena. Stone & well. CC0 texture.

Source Unknow

Disks pattern #1890
 Dark  CC 0

Remixed from a drawing that was uploaded to Pixabay by DavidZydd

Source Firkin

Mix & Black Pattern #1634
 Metal  CC 0

Metal-Plain or Painted. CC0 License.

Source Unknow

Wide Rectangles #699
 Wall  CC BY-SA 3.0

Simple wide squares with a small indent. Fits all.

Source Petr Šulc.

Prismatic Snowflakes Pattern No [email protected] #783
 Light  CC 0

Prismatic Snowflakes Pattern No Background

Source GDJ

Decorative divider 224 #2206
 Dark  CC 0

Remixed from a drawing in 'A Child of the Age', Francis Adams, 1894.

Source Firkin