Hidden Stash
Great place to hide things in your house.
Guns
They have a lot of places to stash stuff.
Cards
Hiding SD cards or money in plain sight.
Toys
Some people are not looking in the right places. A box of Legos is another place to hide things.
Tissue Boxes
Tissue boxes are great but air freshener are another thing you can use.
Magazine and Books
That will take time to look through.
The Wall
Power outlets and picture frames are good but use some thing that is hard to get to.
Foods
Some times people forget to check foods.
Fish Tank
Just get a plastic bag fill it with stuff and then put it under the gravel.