Green Fibers #91
 Dark  CC BY-SA 3.0

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

Source Matteo Di Capua

 More Textures
Fabric 1@2X #10
 Light  CC BY-SA 3.0

Semi-light fabric pattern made out of random pixels in shades of gray.

Source Atle Mo

Background pattern 225 (colour 6) #2322
 Brown  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 design 91 #1814
 Dark  CC 0

From a drawing in 'Hubert Montreuil, or the Huguenot and the Dragoon', Francisca Ouvry, 1873.

Source Firkin

flower seamless pattern-remix #2445
 Fabric  CC 0

This is a remix of "flower seamless pattern".I rotated the original image by 90 degrees.This is a seamless pattern of flowers.These horizontal wavy lines are one of Edo patterns which is called "tatewaku or tachiwaku or 立湧" that represents uprising steam or vapor.

Source Yamachem

Colorful Stripes Background #400
 Noise  CC 0

Colorful Stripes Background

Source GDJ

Floral Abstract Pattern Background #217
 Noise  CC 0

PDP

Source GDJ

Hibiscus Flowers Seamless Background #229
 Fabric  CC 0

PDP

Source GDJ

Prismatic Dots Background@2X #502
 Noise  CC 0

Prismatic Dots Background

Source GDJ

Wine Cork #33
 Light  CC BY-SA 3.0

Wine cork texture based off a scanned corkboard.

Source Atle Mo

Seamless Core Pattern #165
 Dark  CC 0

Seamless Core Pattern

Source GDJ

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

MBossed@2X #194
 Grid  CC BY-SA 3.0

Embossed lines and squares with subtle highlights.

Source Alex Parker

Prismatic Dots Background 8 #515
 Noise  CC 0

Prismatic Dots Background 8

Source GDJ