More Textures
Green Fibers@2X #92
 Dark  CC BY-SA 3.0

The green fibers pattern will work very well in grayscale as well.

Source Matteo Di Capua

Diagonal Noise #181
 Fabric  CC BY-SA 3.0

A simple but elegant classic. Every collection needs one of these.

Source Christopher Burton

Prismatic Groovy Concentric Background 5 No Black #467
 Dark  CC 0

Prismatic Groovy Concentric Background 5 No Black

Source GDJ

Tessellation 15 (colour 4) #2219
 Green  CC 0

The unit cell for this seamless pattern can be had in Inkscape by selecting the rectangle and using shift+alt+i.

Source Firkin

Background pattern 227 (colour 5) #2310
 Colorful  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 4 No Black@2X #442
 Dark  CC 0

Prismatic Abstract Geometric Background 4 No Black

Source GDJ

Retro Circles Background 6@2X #429
 Noise  CC 0

Retro Circles Background 6

Source GDJ

Prismatic Dots Background 4 #507
 Noise  CC 0

Prismatic Dots Background 4

Source GDJ

Hibiscus Flowers Seamless Background #229
 Fabric  CC 0

PDP

Source GDJ

Background pattern 105@2X #564
 Dark  CC 0

A seamless pattern formed from background pattern 102

Source Firkin