Fabric pattern 2 (colour 3) #2394
 Fabric  CC 0

Not a pattern for fabrics, but one produced from a jpg of a stack of fabric items that was posted on Pixabay. The tile that this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i.

Source Firkin

 More Textures
Dark Circles #306
 Dark  CC BY-SA 3.0

People seem to enjoy dark patterns, so here is one with some circles.

Source Atle Mo

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

Prismatic Groovy Concentric Background 4 No Black

Source GDJ

Light Grey Floral Motif #344
 Wall  CC BY-SA 3.0

Lovely light gray floral motif with some subtle shades.

Source GraphicsWall

Background pattern 215 (colour 3) #2369
 Pink  CC 0

A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.

Source Firkin

Background pattern 302 #1894
 Red  CC 0

The tile this fill pattern is based on can be had by using shift+alt+i on the rectangle.

Source Firkin

Prismatic Groovy Concentric Background@2X #450
 Noise  CC 0

Prismatic Groovy Concentric Background

Source GDJ

Zodiac sign symbol background #1927
 Red  CC 0

Just the symbols of the signs of the zodiac distributed in a chequer board-like pattern

Source Firkin

Background pattern 265 #2081
 Dark  CC 0

Remixed from a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892. The tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i

Source Firkin

Dark Leather #129
 Dark  CC BY-SA 3.0

You were craving more leather, so I whipped this up by scanning a leather jacket.

Source Atle Mo

Prismatic Abstract Geometric Background 4 No Black #441
 Dark  CC 0

Prismatic Abstract Geometric Background 4 No Black

Source GDJ

Zig-zag pattern 2 #2417
 Grid  CC 0

A seamless pattern based on a rectangular tile that can be retrieved in Inkscape by selecting the rectangle and using shift-alt-i.

Source Firkin