Here is a work in progress (sorry it's blurry).
Note: It's all foam except hidden brick in middle, skull (home depot) and plants (hobby lobby)
1: Glued 2x 2" thick form board together
2: Cut the foam board down into "rock" sizes and shaped appropriately (i.e.: randomly)
3: Cut post 4"w x 4"d (approximately 3' long)
4: hot glued post to a brick to give it some weight
5: hot glued the rocks together and to the base of the post
6: can of "Great Stuff" (cracks) and filled in gaps between rocks, which formed the dirt.
7: Added cross piece w/ carved words (don't want to carve once mounted)
8: Gave it a base prime coat (brown for cross and grey for rocks/dirt).
9: added some plastic plants from "Hobby Lobby" Just stuck them in along with wood branch from dead tree (back yard)
10: second coat of paint
11: dry brushed light brown/grey
12: corpsed the skull
13: (not done yet) add some fake moss
14: seal with spray coat of clear enamel.
Hope this helps.