More Textures
Darth Stripe@2X #100
 Dark  CC BY-SA 3.0

Diagonal lines with a lot of texture to them.

Source Ashton

Visual illusion #2586
 Grid  CC 0

The edges of all the red objects line up either vertically or horizontally, but it doesn't appear so. Made from a square tile that can be got by selecting the rectangle in Inkscape and using shift+alt+i.

Source Firkin

Prismatic Polka Dots Mark II 2 No Background #532
 Noise  CC 0

Prismatic Polka Dots Mark II 2 No Background

Source GDJ

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

Prismatic Abstract Geometric Background 2 No Black

Source GDJ

Carbon Fiber v2 #105
 Carbon  CC BY-SA 3.0

One more updated pattern. Not really carbon fiber, but it’s the most popular pattern, so I’ll give you an extra choice.

Source Atle Mo

Background pattern 104@2X #562
 Dark  CC 0

Background pattern 104

Source Firkin

MBossed@2X #194
 Grid  CC BY-SA 3.0

Embossed lines and squares with subtle highlights.

Source Alex Parker