There's a great site of textures - which are all photographs - www.cgtextures.com You can use them as an overlay and paint, or an overlay of the texture itself for a different kinda feel - totally up to your tastes.

It's free - you have a 15MB download limit per day - and they have lots of images (including fabrics) in every category you can think of. You CAN get a subscription where your dowload limit goes up significantly - I think it starts at $80 per year for 100MB per day downloads.

Glad these can help - have fun!
-Lew ;-)