* Found as in discovered: Εὗρον (heuron) is the first person singular aorist active indicative of εὑρίσκω (heurisko), meaning "to find." This is a good translation if you discovered something lost.
* Found as in established: Ίδρυσα (idrysa) is the first person singular aorist active indicative of ιδρύω (idryō), meaning "to found" (as in to establish a city, organization, etc.).
* Found as in discovered to be true: Εὕρηκα (heureka), the first person singular perfect active indicative of εὑρίσκω (heurisko), is famous, but it implies a sudden discovery, usually a truth or solution.
Therefore, the best Greek word depends heavily on the context of what was "found."