I've been asked how I did the farmer's fields on my Town of Riverfield map so here I am. I used Photoshop 7.0 to create my farmer's fields but I would think this should work with later Photoshop versions and perhaps with GIMP (some of the finer details may be different but the basics should be the same).
Step 1 – Creating the Basic Field: Create a rectangle or square shape with the Rectangle Marquee Tool on its own layer. Fill the selected area with a colour of your choice. I used earthy colours but not too dark because the lines that will go above this layer should be darker to represent the lines in the field. Once you have filled the selected area with a chosen colour, apply a Noise Filter (amount = 5.41, uniform, monochromatic) to it. You should get something that looks like this:
Step 2 – Creating the Field Lines: On a new layer above the basic field, select the Brush Tool. In the example below, I used a Brush with a diametre of 5px. Before you start to draw, go into the Brush Palette and select the Scattering option from the Brush Tip Shape (Scatter 142%/Control: Off, Count 1, Control Jitter 0%/Control: Off). Now draw a straight line down the far side of the field. You should get something that looks like this:
The next step is to duplicate the field line layer and moved it over a little to the right. You now have two field line layers. You could draw a new line but I find duplicating it gives me consistent results with the line that I might not have done so by drawing all of them free hand. You may wish to use the Transform Option to rotate the new line 180 degrees (Edit -> Transform -> 180 degrees) to help give the field lines a bit of irregularity. You should get something that looks like this:
Merge the new field line layer back into the previous field line layer layer (now there are two lines on the one layer). Duplicated that layer again and move the results to the right. Merged the new layer backed into the old one and now there are four lines instead of two. Repeat this process until you get enough lines to fill the field. This will quickly fill up the field because of exponential growth (1 line -> 2 lines -> 4 lines -> 8 lines -> 16 lines, etc). Erase any lines that may spill over. You should get something that looks like this:
Step 3 – Creating the Full Field: Once you have created a field you are happy with, merge the Field Line Layer with the Basic Field Layer. You may wish to use this image as your template, in that case duplicate the layer and hide the template layer (for future use). Using the methods listed above, I create several different fields with different colour schemes. I then use the Transform Tool to put these various fields together in a way that looks good. You could get something that looks like this:
This is just an example of what you can do. The ultimate combination of colours, sizes and or fields is up to you. I hope this made sense.