Candyhole #356
 Light  CC BY-SA 3.0

It’s a hole, in a pattern. On your website. Dig it!

Source Josh Green

 More Textures
Diamond pattern 2 (colour 5) #2264
 Blue  CC 0

From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.

Source Firkin

Retro Squares Background #414
 Noise  CC 0

Retro Squares Background

Source GDJ

Decorative divider 229 #2151
 Dark  CC 0

From a design found in 'History of the Virginia Company of London; with letters to and from the first Colony, never before printed', Edward Neill, 1869.

Source Firkin

Subtle Orange Emboss #97
 Light  CC BY-SA 3.0

A hint of orange color, and some crossed and embossed lines.

Source Adam Anlauf

Brushed Alum@2X #68
 Light  CC BY-SA 3.0

A light brushed aluminum pattern for your pleasure.

Source Tim Ward

Checkered Pattern@2X #323
 Grid  CC BY-SA 3.0

Simple gray checkered lines, in light tones.

Source Radosław Rzepecki

Prismatic Abstract Geometric Background #269
 Noise  CC 0

Prismatic Abstract Geometric Background derived from an image on Pixabay.

Source GDJ

Axiom Pattern@2X #331
 Grid  CC BY-SA 3.0

Not even 1kb, but very stylish. Gray thin lines.

Source Struck Axiom

Project Papper@2X #120
 Paper  CC BY-SA 3.0

Light square grid pattern, great for a “DIY projects” sort of website, maybe?

Source Rafael Almeida

Prismatic Abstract Geometric Background 4 No Black@2X #443
 Dark  CC 0

Prismatic Abstract Geometric Background 4

Source GDJ