The Hammond Foundation was founded by John Hammond prior to the events in the first Jurassic Park Novel. The foundation would donate funds to many dig sites as well as buy products like Amber, synthetic eggshells, and fossils.
Founded in 1979, the Foundation only funded dinosaur digs in the north. In the mid-80s, it leased Isla Nublar from the Costa Rican government under the guise of setting up a biological preserve/tourist resort facility. Due to this, the Foundation is simply a large part of John Hammond's playbook to hide deals that the U.S. government might have tried to use to intervene with InGen and his parks.