Last year I picked up a cookie coffin and a cookie grave yard at Target for just a couple of bucks. I dug it out and Mason and I put it together. It's just like the pre-cut cookie houses from Wilton - comes with frosting, fondant, cookie pieces and spooky decorative candy pieces. We had a lot of fun.
A grave yard would be easy to do if you had those mini (or regular size) Pepperidge Farm Milano cookies as tombstones. You can decorate them and stick them in cupcakes, a sheet cake or on top of a heavily frosted cookie cut into a 8x8 square. Frost the bottom with green frosting and use crushed cookies to resemble dirt.
The Coffin was supposed to be 3-D but the bottom was cracked. It still looked nice.