Smooth Wall #27
 Light  CC BY-SA 3.0

Some rectangles, a bit of dust and grunge, plus a hint of concrete.

Source Atle Mo

 More Textures
Background pattern 315 (colour 6) #1840
 Green  CC 0

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

Source Firkin

Recharging the void #164
 Noise  CC 0

Original effect recreated by a simple filter.

Source Lazur URH

Diagmonds #336
 Dark  CC BY-SA 3.0

Love the style on this one, very fresh. Diagonal diamond pattern. Get it?

Source INS

Paper 3@2X #32
 Paper  CC BY-SA 3.0

Light gray paper pattern with small traces of fiber and some dust.

Source Atle Mo

Background pattern 252 (colour 6) #2157
 Light  CC 0

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

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

“Transparent” Background Pattern #493
 Light  CC 0

An emulated “transparent” background pattern, like that of all kinds of computer graphics software.

Source AdamStanislav

Parquet flooring pattern #2427
 Red  CC 0

A seamless pattern recreated from an image on Pixabay. It is reminiscent of parquet flooring and is formed from a square tile, which can be recovered in Inkscape by selecting the ungrouped rectangle and using shift-alt-I together.

Source Firkin

Background pattern 251 (colour 3) #2165
 Blue  CC 0

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

Source Firkin

Prismatic Groovy Concentric Background #449
 Noise  CC 0

Prismatic Groovy Concentric Background

Source GDJ

Prismatic Geometric Tessellation Pattern 3 No Background@2X #556
 Noise  CC 0

Prismatic Geometric Tessellation Pattern 3 No Background

Source GDJ

Background pattern 105@2X #564
 Dark  CC 0

A seamless pattern formed from background pattern 102

Source Firkin

Checkered Light Emboss@2X #281
 Grid  CC BY-SA 3.0

Sort of like the Photoshop transparent background, but better!

Source Alex Parker