WaveCut #75
 Light  CC BY-SA 3.0

If you like it a bit trippy, this wave pattern might be for you.

Source Ian Soper

 More Textures
Colorful Geometric Pattern Background #231
 Noise  CC 0

PDP

Source GDJ

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

Cubes@2X #134
 Light  CC BY-SA 3.0

This reminds me of Game Cube. A nice light 3D cube pattern.

Source Sander Ottens

Double Lined@2X #52
 Stripes  CC BY-SA 3.0

Horizontal and vertical lines on a light gray background.

Source Adam Anlauf

Lego background #266
 Noise  CC 0

Background formed from the iconic plastic construction bricks that gave me endless hours of fun when I was a lad.

Source Firkin

Black And White Floral Pattern Background Inverse #197
 Dark  CC 0

Black And White Floral Pattern Background from PDP.

Source GDJ

Gold Scale@2X #285
 Light  CC BY-SA 3.0

More Japanese-inspired patterns, Gold Scales this time.

Source Josh Green

Black And White Floral Pattern Background Inverse #196
 Dark  CC 0

Black And White Floral Pattern Background Inverse

Source GDJ

Clover with background #237
 Paper  CC 0

Clover with background for St. Patrick's Day. Add to a card with a doily, ribbon, a leprechaun or other embellishments.

Source BAJ

Background pattern 306 (colour 5) #1879
 Colorful  CC 0

Seamless pattern the tile for which can be had by using shift-alt-I on the selected rectangle in Inkscape.

Source Firkin

Brushed Alum Dark #65
 Dark  CC BY-SA 3.0

Because I love dark patterns, here is Brushed Alum in a dark coating.

Source Tim Ward