I am planning on making a raised bed of sorts for my chicken run, cover the top in hardware cloth and plant some type of grass or weeds in it...(so they have access to green but can't obliterate it! We can't free range bc of our dogs, cats and other preditors)
		
		
	 
In part of my chicken run, I put down a grazing frame. A grazing frame is simply some 2X4's or 2X6's framed up to hold hardware cloth on top. The grass grows up and through the hardware cloth and the chickens can eat the top parts of the grass without being able to dig or pull up the grass by the roots. It's very simple to build. In theory, it works really well.
Google picture of a grazing frame - not my chicken run...
OK, so my grazing frames has not worked out so well for me, and here is why. First of all, I used standard 2X4's for the frame and hardware cloth on top. At first, everything was working well for me. But I have also turned my chicken run into a chicken run composting system, and the litter (grass clippings, leaves, wood chips, organic weeds from garden, etc...) is about 18 inches deep in most parts of the chicken run. Well, over time, the chickens have started to scratch the compost litter on top of the grazing frame, blocking the sunlight, and the grass does not grow like it used to.
Now that I'm into pallet projects, I think I will pull out that old grazing frame and add another 2X4 (3-1/2 inches tall) to the bottom of the frame. That should make the grazing frame 7 inches tall which would prevent the chickens from covering the top of the wire from their scratching the compost litter around the run.

 Here is another pallet project idea I just thought of. Why not take a pallet, remove all the inner planks both top and bottom, put some hardware cloth on the top of the pallet, and plop it down on the ground as an instant grazing frame! How simple is that?!
You could certainly build a raised bed, as you mentioned, with a hardware top, and there would be advantages to that as well. I'm all into raised beds for my gardening. 


 Bonus idea... Why not just take 2 or three pallets, add some 2X4's (or planks of the same size) to the ends to close them off, remove all the planks top and bottom, stack the pallet frames, and call that a raised bed? If you wanted to make it look better, cut the planks to your height and then use the planks to dress up the outside of the frames.