How did a Roman legion prove that someone was worthy/actually won a mural or grass crown?

Question

Mural crown: First man over the walls during a siege of a fortified settlement.

Grass grown: Rarest and most prestigious award in Rome’s military history, awarded to a man who single handed-idly saved the army through his actions and could only be made/given by soldiers, not commanders

In: 74

Answer 1

You don’t really need proof as such, if you have enough troops saying a heroic action happened, that’s enough. Conversely, if nobody saw a heroic act, did it really happen?

The notion that objective truth matters and things need to be proved or disproved in absolute, that’s a characteristic of modern western culture, not of ancient Rome, or ancient anywhere really, “they say” was all that mattered.