These were made using a number of different tools, texture creation software specifically, using a mix of gradients/filters/remapping/combining/blending
Genetica, WC3 [unavailable], Texture Maker, Wood Workshop, little bit of GIMP/Photoshop
Some have been made using actual photographs (Mostly grass/dirt textures) and edited using the synthesis node of Genetica, some have been made using different combinations of patterns and random noise, while still others are modified combinations of prebuilt snippets (some tiles/walkways/etc) that would be useful for many projects!