Smooth Wall #27
 Light  CC BY-SA 3.0

Some rectangles, a bit of dust and grunge, plus a hint of concrete.

Source Atle Mo

 More Textures
Background pattern 328 (colour 4) #1798
 Green  CC 0

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

Source Firkin

Prismatic Abstract Geometric Background 4 No Black@2X #442
 Dark  CC 0

Prismatic Abstract Geometric Background 4 No Black

Source GDJ

Background pattern 235 (colour 6) #2250
 Red  CC 0

To get the tile this is formed from select the rectangle in Inkscape and use shift+alt+i.

Source Firkin

Background pattern 252 (colour 3) #2160
 Green  CC 0

Recreated from a pattern found in 'Az Osztrák-Magyar Monarchia irásban és képben', 1882. To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.

Source Firkin

Vintage Elegant Floral Background #257
 Fabric  CC 0

PDP

Source GDJ

Small Crosses@2X #116
 Stripes  CC BY-SA 3.0

Sharp pixel pattern looking like some sort of fabric.

Source Dmitry

Background pattern 339 (colour 2) #1707
 Green  CC 0

The tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i

Source Firkin

Prismatic Geometric Tessellation Pattern 2 No Background@2X #554
 Noise  CC 0

Prismatic Geometric Tessellation Pattern 2 No Background

Source GDJ