Mostly those from Flypaper Textures (I pay for those and have enough now) and Shadowhouse Creations (free). Both are free to use. Mostly I combine textures in layers and then work with blending modes for an interesting effect. dA has some great textures as well, but somewhat a hassle to link the use back and forth - bit I have done it.
Yes - flypaper are rather nice! They do some beautiful work and a lot of them already have the edges burned. I make all my own textures( except for in phone edits) and it took awhile to get the opacity right but well worth the effort