Background pattern 254 (colour) #2143
 Colorful  CC 0

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

Source Firkin

 More Textures
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

Old Mathematics@2X #44
 Stripes  CC BY-SA 3.0

This one takes you back to math class. Classic mathematic board underlay.

Source Josh Green

Seamless Prismatic Geometric Pattern With Background #264
 Dark  CC 0

Seamless Prismatic Geometric Pattern With Background

Source GDJ

Background pattern 224 (colour 2) #2341
 Colorful  CC 0

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

Source Firkin

Background pattern 223 #2353
 Red  CC 0

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

Source Firkin

Prismatic Curved Diamond Pattern 6 No Background@2X #546
 Dark  CC 0

Prismatic Curved Diamond Pattern 6 No Background

Source GDJ

Retro Circles Background 4 #420
 Dark  CC 0

Retro Circles Background 4

Source GDJ

"Glossy Pink Fur", Pink Background Pattern #1235
 Pink  CC BY-SA 3.0

Here's a quite bright pink background pattern for use on websites. It doesn't look like a real fur, but it definitely resembles one.

Source V. Hartikainen

Diamond pattern (colour 6) #2280
 Yellow  CC 0

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

Source Firkin