She seems to keep things right out in the open or in easily accessible locations presumably because she feels no one is on to her and she has nothing to fear up until this point.
That room screams everything that she is to anyone who walks in, but no one (with the exception of Mr Gold, and possibly Henry) has any idea. She’d love that. What a way to flaunt the power she has over everyone.
Sooo what’s in that very large, obvious chest on her desk I wonder????
Who knows what (if anything) she keeps in it now, but it was the chest she put her father’s heart in when she took it to toss it in the fire and enact the curse.