Patern dots #241
 Dark  CC 0

Pattern repeating background 48x48

Source Keistutis

 More Textures
Colorful Floral Background No Black@2X #482
 Light  CC 0

Colorful Floral Background No Black

Source GDJ

Background pattern 9 (colour) #214
 Noise  CC 0

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

Source Firkin

Background pattern 215 (colour 4) #2368
 Green  CC 0

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

Source Firkin

Decorative divider 254 #2040
 Dark  CC 0

Remixed from a design seen in 'Burghley. The Life of William Cecil', William Charlton, 1857

Source Firkin

Background pattern brown #1951
 Brown  CC 0

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

Source Firkin

Hexagonal pattern #2379
 Dark  CC 0

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

Source Firkin

Batthern #324
 Grid  CC BY-SA 3.0

Sometimes simple really is what you need, and this could fit you well.

Source Factorio.us Collective

Dark Stripes #39
 Dark  CC BY-SA 3.0

Very dark pattern with some noise and 45-degree lines.

Source Stefan Aleksić

Brushed Alum #67
 Light  CC BY-SA 3.0

A light brushed aluminum pattern for your pleasure.

Source Tim Ward