It is a symbol of conflicts, looking for solutions, uncertainty, helplessness. A tomb is of course associated with death, so the dream about the grave can be a harbinger of death, or the definitive break-up. There may be also involved the failure of some plan.
see someone digging a grave: bad news about the death of a beloved person
to descend to the grave: backbiting, slanders
an open grave: cheerful fun awaits you
see an opening tomb: a person from the past, you wanted to forget, still has a big impact on you
empty: the loss of friends and loneliness
see falling: bad luck, illness in the family
put flowers on the grave of your mother: looking for consolation
see a name written on the grave: beware of your health
die and be buried: the death of a friend
burial mound: the long-forgotten things will become reveled or you will find a lost thing
a tombstone: the return of an old friend, who won respectability in the world
read the inscription on the tombstone: loss of your comrade
a gravestone: blessing in marriage and prosperity
if you grew flowers on the grave: something dead or dying reborn in spite of everything; it may be friendship, love, etc..
if around the cross or tombstone climbs ivy: bad omen; you are a prisoner of memories and this obsession does not allow you to live a normal life; it is also possible that you are neurotic, sick, and it prevents you from functioning in life