Grilled Noise #581
 Fabric  CC BY-SA 3.0

You could get a bit dizzy from this one, but it might come in handy.

Source Dertig Media

 More Textures
Fake Brick #358
 Dark  CC BY-SA 3.0

Black, simple, elegant, and useful.

Source Marat

Tessellation 16 #2215
 Yellow  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

Interlocking pattern 3 (colour 2) #2405
 Grid  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

Prismatic Dots Background 3 #505
 Noise  CC 0

Prismatic Dots Background 3

Source GDJ

Background pattern 226 (colour 2) #2320
 Green  CC 0

A seamless pattern from a tile made from a jpg on Pixabay. To get the tile select the rectangle in Inkscape and use shift-alt-i.

Source Firkin

Background pattern 254 (colour) #2143
 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 308 (colour 2) #1871
 Green  CC 0

Design drawn in Paint.net, vectorised using Vector Magic and finished in Inkscape.

Source Firkin

Blue Wallpaper For Websites #910
 Stripes  CC BY-SA 3.0

A blue background wallpaper for websites. It has a seamless texture with vertical stripes. It looks quite nice not only when using as a tiled background on websites, but also on computer desktops.

Source V. Hartikainen

Zodiac pattern (black background) #267
 Dark  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. Version with black background.

Source Firkin

"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

Background pattern 9 (greyscale) #213
 Dark  CC BY-SA 3.0

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

Source Firkin

Art Nouveau ornament-seamless pattern #2550
 Brown  CC 0

This is the remix of an OCAL clipart called "Art Nouveau ornament" uploaded by "microcosme".Thanks.This is a seamless pattern of an Art Nouveau ornament.

Source Yamachem

Seamless Prismatic Quadrilateral Line Art Pattern No Background #379
 Diamond  CC 0

Seamless Prismatic Quadrilateral Line Art Pattern No Background

Source GDJ

Wood Pattern #370
 Wood  CC BY-SA 3.0

One of the few full-color patterns here, but this one was just too good to pass up.

Source Alexey Usoltsev