Gun Metal@2X #361
 Dark  CC BY-SA 3.0

With a name this awesome, how can I go wrong?

Source Nikolay Boltachev

 More Textures
Retro Squares Background 7 #397
 Noise  CC 0

Retro Squares Background 7

Source GDJ

Background pattern 225 (colour 4) #2324
 Green  CC 0

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

Source Firkin

Floral pattern 9 #2043
 Dark  CC 0

The tile can be had by selecting the rectangle in Inkscape and using shift+alt+i. Remixed from a drawing in 'Flowers of Song', Frederick Weatherly, 1895.

Source Firkin

Prismatic Abstract Geometric Background 4 #271
 Noise  CC 0

Prismatic Abstract Geometric Background 4

Source GDJ

Background pattern 201 #2501
 Grid  CC 0

A pattern formed from a squared tile. The tile can be accessed in Inkscape by selecting the rectangle and using shift-alt-i.

Source Firkin

Prismatic Groovy Concentric Background 4 No Black #463
 Noise  CC 0

Prismatic Groovy Concentric Background 4 No Black

Source GDJ

Prismatic Groovy Concentric Background 5 No Black@2X #468
 Dark  CC 0

Prismatic Groovy Concentric Background 5 No Black

Source GDJ

Background pattern 226 (colour 2) #2320
 Green  CC 0

A seamless pattern from a tile made from a jpg on Pixabay. To get the tile select the rectangle in Inkscape and use shift-alt-i.

Source Firkin

Axiom Pattern@2X #331
 Grid  CC BY-SA 3.0

Not even 1kb, but very stylish. Gray thin lines.

Source Struck Axiom