Burying Items in Sand/Gravel to Make your Own Suspicious Blocks

There are already a number of dig sites naturally generating in the world, so I think players should be able to create their own for others to explore (especially, but not exclusively in Adventure Maps). I think crafting an item with sand or gravel would be too hard to code for all the different items in the game and also not fit with how the items in natural Suspicious Blocks got there. They fell and, over time, sifted down into the rubble instead of being placed there on purpose..

Therefore, I offer a solution to this. If you throw an item on sand or gravel it should stay there in case you accidentally dropped it, but instead of despawning after 5 minutes it would create Suspicious Sand or Gravel beneath it. I also think that the block should be able to hold at least a Chest's worth of items and have them sifted out a stack at a time. These additional features would open up the possibility of a Player placing sand or gravel beneath them as a safety measure so their dropped items don't despawn in case of death and they can recover them with a Brush afterwards.