No, we'd need a plural to justify using "are". "What things are there in your bed?" This also assumes that your bed has several things in it. By the way, do you mean "bed" or "bedroom"?
It's natural to ask a singular question if we don't know whether the answer will be one or many.
"What's in your bed?" (we don't even need "there")
"Who was at the party?" (yes, the answer can be a list of people)
"What's in the fridge?"