Snap! It’s a pattern, and it’s not grayscale! Of course you can always change the color in Photoshop.
Source Atle Mo
Looks a bit like concrete with subtle specks spread around the pattern.
Source Mladjan Antic
Number five from the same submitter, makes my job easy.
Source Dima Shiper
To get the repeating unit, select the rectangle in Inkscape and use shift+alt+i
Source Firkin
From a drawing in 'Studies for Stories', Jean Ingelow, 1864.
Source Firkin
A pale olive green background with a seamless texture.
Source V. Hartikainen
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Background formed from the original with an emboss effect.
Source Firkin
Prismatic Snowflakes Pattern 3 No Background
Source GDJ
People seem to enjoy dark patterns, so here is one with some circles.
Source Atle Mo
Alternative colour scheme. 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
A seamless striped fabric-like texture colored in a dark reddish brown color.
Source V. Hartikainen
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Inspired by a drawing in 'Poems', James Smith, 1881.
Source Firkin
A repeating background with a look of paper. I have added some changes to PatCreator. Now you can share your designs by submitting them to a new gallery section. Start by clicking Edit with PatCreator above.
Source V. Hartikainen
This light background pattern has a texture of "frozen" surface with diagonal stripes. Here's an yet another addition to the collection of free website backgrounds.
Source V. Hartikainen
Got some felt in my mailbox today, so I scanned it for you to use.
Source Atle Mo
Prismatic Abstract Geometric Background 4
Source GDJ
Zero CC asphalt, pavement, texture, photographed and made by me. CC0 WARNING I FOUND A SEAM ON THIS TEXTURE
Source Sojan Janso