When information is hidden in a dream it is most likely that at this stage we have not progressed enough spiritually to be able to handle it.
Psychological / emotional perspective: In waking life we become very good at hiding our emotions.
A dream in which we must make an effort to uncover something suggests we perhaps need to understand why we do this. When an object is hidden in dreams we may have to first give ourselves permission to reveal whatever it represents.
To find a hidden jewel perhaps suggests a hidden talent.
Material aspects: To be hiding something suggests we have issues over our own personal privacy or sense of value.
If we dream that someone is hiding something from us it may suggest a lack of trust in either direction.