Background pattern 291 #1931
 Dark  CC 0

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

Source Firkin

 More Textures
White Grunge Background #1124
 Grunge  CC BY-SA 3.0

This white background pattern has a seamless grunge style texture. Here's a white grunge style background pattern. Use it as a tiled background image on web sites or for other purposes.

Source V. Hartikainen

Background pattern 29 #200
 Dark  CC 0

Pattern produced in Paint.net using the Vibrato plug-in.

Source Firkin

Prismatic Groovy Concentric Background #449
 Noise  CC 0

Prismatic Groovy Concentric Background

Source GDJ

Graphy #350
 Grid  CC BY-SA 3.0

Looks like a technical drawing board: small squares forming a nice grid.

Source We Are Pixel8

"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

Paper 2 #21
 Paper  CC BY-SA 3.0

New paper pattern with a slightly organic feel to it, using some thin threads.

Source Atle Mo

Tessellation 16 (colour 2) #2214
 Colorful  CC 0

The unit cell for this seamless pattern can be had in Inkscape by selecting the rectangle and using shift+alt+i.

Source Firkin

Prismatic Octagonal Background #439
 Noise  CC 0

Prismatic Octagonal Background

Source GDJ

Prismatic Curved Diamond Pattern 6 No Background@2X #546
 Dark  CC 0

Prismatic Curved Diamond Pattern 6 No Background

Source GDJ

Background pattern 314 (colour 3) #1837
 Green  CC 0

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

Source Firkin

Background pattern 235 (colour 2) #2254
 Blue  CC 0

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

Source Firkin

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

Prismatic Hypnotic Pattern 2 No Background #573
 Noise  CC 0

Prismatic Hypnotic Pattern 2 No Background

Source GDJ

Pinstripe #35
 Light  CC BY-SA 3.0

Light gray pattern with a thin pinstripe.

Source Brandon

Retro Circles Background 5@2X #425
 Noise  CC 0

Retro Circles Background 5

Source GDJ

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