Background pattern 302 (colour 2) #1893
 Dark  CC 0

The tile this fill pattern is based on can be had by using shift+alt+i on the rectangle.

Source Firkin

 More Textures
Background pattern 224 (colour 3) #2340
 Colorful  CC 0

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

Source Firkin

Fabric pattern 3 (colour 6) #2382
 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

Retro Circles Background 5 No Black #426
 Noise  CC 0

Retro Circles Background 5 No Black

Source GDJ

Seamless Core Pattern 2 #166
 Dark  CC 0

Seamless Core Pattern 2

Source GDJ

Psychedelic Geometric Background #381
 Noise  CC 0

Psychedelic Geometric Background.

Source GDJ

Background pattern 298 #1899
 Dark  CC 0

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

Source Firkin

Background pattern 226 (colour 5) #2317
 Blue  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

Dark Denim #372
 Dark  CC BY-SA 3.0

Thin lines, noise and texture creates this crisp dark denim pattern.

Source Marco Slooten

Desert Camo Print #255
 Fabric  CC 0

Here's a camo print with more tan and less green, such as might be used in a desert scenario. This is tileable, so it can be used as a wallpaper or background.

Source Eady

White Texture #131
 Light  CC BY-SA 3.0

Not the most creative name, but it’s a good all-purpose light background.

Source Dmitry