More Textures
Transparent Square Tiles #298
 Grid  CC BY-SA 3.0

The first pattern on here using opacity. Try it on a site with a colored background, or even using mixed colors.

Source Nathan Spady

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

Prismatic Rounded Squares Grid 3 No Background #489
 Noise  CC 0

Prismatic Rounded Squares Grid 3 No Background

Source GDJ

Prismatic Chevrons Pattern 5 With Background #469
 Dark  CC 0

Prismatic Chevrons Pattern 5 With Background

Source GDJ

Subtle Freckles #89
 Light  CC BY-SA 3.0

This is so subtle: We’re talking 1% opacity. Get your squint on!

Source Atle Mo

Background pattern 227 (colour 2) #2313
 Blue  CC 0

A seamless background drawn in Paint.net and vectorised with Vector Magic. The starting point was a photograph of drinking straws from Pixabay.

Source Firkin

Prismatic Abstract Geometric Background 2 No Black@2X #446
 Noise  CC 0

Prismatic Abstract Geometric Background 2 No Black

Source GDJ

Background pattern 4 #223
 Noise  CC 0

A pattern derived from repeating unit cells each derived from part of a mosaic in paint.net. The starting point for the mosaic was a picture of some prawns!

Source Firkin

Faded Yellow Stripes, Background Pattern #1218
 Yellow  CC BY-SA 3.0

A pale yellow background pattern with vertical stripes. The stripes are partially faded. I think this background image turned out pretty well, especially those faded stripes.

Source V. Hartikainen

Geometric pattern #2002
 Dark  CC 0

A monochrome pattern from a tile that can be had by selecting the rectangle in Inkscaope and using shift+alt+i

Source Firkin

Prismatic Abstract Geometric Background 2 #268
 Noise  CC 0

Prismatic Abstract Geometric Background 2

Source GDJ