I present one here, warning you that I mistrust definitions of symbols. Fans of Jung seeking to transcend their present consciousness will be dissatisfied with this list because I do not believe in universals. We possess endlessly creative minds which can take a word, an object, or an idea and transform or transmogrify it into something new. Many people who choose grave motifs have no idea what they are putting on their stones. What they know is that they like the design.
Symbols can express ethnic identity, religion, association, or the good taste of the time.
Ask them why and you will hear them descend into circular reasoning. By all means, when you walk through a cemetery, amuse yourself by looking at the details of the stones. There's no harm in evaluating the monuments using what you have read or otherwise know. Be warned, however, that each cemetery is a peculiar place. Symbols which often mean one thing may have a different local meaning.