The Complete Guide to Interpreting Your Dreams

by Stearn Robinson - Tom Corbett
Sadness (but not grief) may be expected following a dream of a casket containing a body, but a dream of contrary indicating good luck if the body was your own.

An empty casket signified a lost friend, but not necessarily through death.

See also Funeral, Death, etc.

Strangest Dream Explanations

by Dream Explanations - Anonymous
Dreams of a casket symbolize your feelings and attitudes about death, change and transition in relationships or business. Dreams of a casket are also about being contained and supported while you move from one phase of your life to the next.

See Death.

Complete Dictionary of Dreams

by Dr. Mıchael Lennox
The implication of a casket is that someone has died. Any death is symbolic of the rebirth that will follow.

The casket itself represents the ability to contain the process of change and transformation that a death implies.