Most of us who have the scenery building itch probably have a hot glue gun around. Fantastically useful things for gluing scenery projects together quickly and securely. Also good for burning your fingertips if you aren't careful - even "low temp" hot glue is still, amazingly, actually pretty hot, and a blob of it can retain it's heat for a while.
Anyway, some time ago I was messing around with my hot glue gun and realized that cooled glue retains it's shape. The stuff doesn't spread out like most other glues do. So I grabbed a scrap of plastic sheet and bashed together a small plowed field, with the ridges from the plowing and some of the shape around the edge of the field provided by cheap, easy to use hot glue.
Getting bored of painting Russians, last night I broke out a 12"x11" piece of salvaged 3mm plastic sheeting. I salvaged it intending to make buildings from it, but it's too hard to cut and won't glue with superglue or regular plastic solvent cement. It makes grand scenic bases, though. A quick bit of cutting got me six rectangular fields, each just a bit under 6"x4" in size. I used razor knife and sandpaper to smooth the corners and edges down, then got to work with the hot glue gun.

One of them got a bit of rock wall, and I varied the length and facing of the plowing on a few just for interest. There's a few paths and muddy patches, too.
Right after work tonight, I got out the white glue and my mixed-sand-and-grit "dirt texture" mix and slapped a layer of that down.

That dried in a few hours, so I was just able to slap the basecoat of paint on, which is 2 parts basic brown craft paint and 1 part white glue, to really lock the sand down and keep it in place. I used an even darker brown to pick out some of the muddier low-lying bits.

Tomorrow after work (possibly even before work, if I'm a very organized animal...) I'll be able to whip through the base coat on the rock wall, then the drybrushing of the dirt and rocks. A bit of mixed foliage as crops and weeds, and I'll have another set of solid, gamer-proof, easily transported pieces of texture for the tabletop. I can't stand a blank stretch of felt where there's a possibility of putting something down to add texture and interest to the table, so these will suit perfectly.
The rock walls you can see on the CD base, one field and the tongue depressor are all from medium "decor" gravel and Gorilla Glue, which is fun stuff for scenery building too. It's an easy way to make ragged, unkempt rock walls. More on that later.