Soft Circle Scales #113
 Light  CC BY-SA 3.0

Japanese looking fish scale pattern.

Source Ian Soper

 More Textures
Background pattern purple #1998
 Colorful  CC 0

Seamless pattern formed from a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i

Source Firkin

Abstract Ellipses Background Grayscale #378
 Dark  CC 0

Abstract Ellipses Background Grayscale

Source GDJ

Prismatic Curved Diamond Pattern 6 No Background #545
 Dark  CC 0

Prismatic Curved Diamond Pattern 6 No Background

Source GDJ

Background pattern 7 (grey) #206
 Dark  CC 0

Greyscale version of a pattern that came out of playing with the 'slinky' plug-in for Paint.net

Source Firkin

Wine waiter pattern #2403
 Colorful  CC 0

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

Source Firkin

Background pattern 213 (colour) #2411
 Colorful  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. A version of the original with random colors.

Source Firkin

Background pattern 215 (colour 2) #2370
 Blue  CC 0

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

Source Firkin

Prismatic Rounded Squares Grid 3 No Background #489
 Noise  CC 0

Prismatic Rounded Squares Grid 3 No Background

Source GDJ

Concrete Wall 2 #79
 Wall  CC BY-SA 3.0

A light gray wall or floor (you decide) of concrete.

Source Atle Mo

Fabric pattern #2402
 Fabric  CC 0

Alternative colour scheme. Not a pattern for fabrics, but one produced from a jpg of a stack of fabric items that was posted on Pixabay. The tile that this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i.

Source Firkin

Broken Noise #364
 Dark  CC BY-SA 3.0

Beautiful dark noise pattern with some dust and grunge.

Source Vincent Klaiber

Background pattern 306 (colour 6) #1878
 Colorful  CC 0

Seamless pattern the tile for which can be had by using shift-alt-I on the selected rectangle in Inkscape.

Source Firkin

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

Abstract Ellipses Background #275
 Dark  CC 0

Abstract Ellipses Background

Source GDJ

Paper 1@2X #16
 Paper  CC BY-SA 3.0

A slightly grainy paper pattern with small horizontal and vertical strokes.

Source Atle Mo