Therefore I've used that idea and made some hedge clumps and smoke markers. I might develop this idea some more, but for now here's what I did.
I purchased some 2mm thick, 20mm diameter MDF pieces. These are available on ebay for only a couple of pounds.
On each of them I added some brown window putty. As I was experimenting I tried a few different finishes with the putty, but the main style I wanted was a cratered finish. Seems like craters are likely when shells and artillery go off and also it makes it very easy to put something in the crater because the crater edges cradle it and hide the glue.
I took two different packets of Javis clump foliage. It's hard and far less malleable that the Woodland Scenics, so it's great to have a use for it because I couldn't seem to use it to make the much larger explosion markers. I put a good splodge of PVA in the crater, added the clump and then waited for it to dry. Then today I added a second liberal coat of PVA, just over the top to seal the hedge down.
I think these will make great little pieces of randomly placed scenery on a board. Put a few of them close together and they might be able to break line of sight between infantry teams.
Then the other type of marker I made this time are smoke markers. Another good blob of PVA goes in the crater well, then a lump of pillow filling, rolled and shaped. Using the pillow filler isn't my idea, I saw someone using it on Youtube for smoke markers.
I hope these work out, I literally finished making these before dinner this evening. I'll try and get some photos of these on a terrain board or in use soon.