There are many fabric designs of interest to tabletop wargamers, available at such shops.
I have found patterns which my wife cut and sewed into a gridded city pattern of mottled green grassy blocks, with mottled gray patterns. She sewed them like a quilt, forming city blocks with gray streets. I used it for my 54mm Army Men games. It is fantastic to set ruined buildings atop!
I found wooded forest type patterns which I used my wife's serger sewing machine to create rolled hems, which prevent fraying. The serger also cuts the fabric, as it sews the rolled hem, allowing me to make oddly shaped oval patterns. I made bunches of these. I lay them atop my ground cloth, often overlapping one another, to form the boundaries of wooded areas, placing model trees on top of them.
I did the same with swamp patterned cloths: cut them into oddly shaped ovals, with rolled hems; overlaying them, on top of each other, to form oddly shaped swamp water patches; I place plastic swamp plants, on painted, decorated bases, on top of the swamp cloths. It makes great terrain areas, with clearly defined boundaries.
Over the years, I have found many cloth patterns and designs which are suitable for many terrain types: star fields for space games; water/ocean patterns for naval games; mottled red/tan/other patterns for deserts, alien worlds, etc. Patterns change, frequently. If you see something you think you can use, buy as much as you think you will ever need, immediately! Otherwise, you will need to wait for the next suitable pattern to appear. Cheers!