To see a key in your dream, symbolizes opportunities, access, control, secrets, or responsibilities. You may be locking away your own inner feelings and emotions.
To dream that you lose your keys, signifies your fear of losing your position or status in life. You may have lost control of yourself. It may also foretells of unexpected changes and unpleasant adventures. If you give your key away, then it suggests that you have given up control of some situation or responsibility.
To dream that you find keys, signifies that you have found a solution to a problem.
I dreamed that my husband gave me his keys and I don't see anything about keys representing trust as I had assumed. I checked a couple of dream dictionaries.