Iris Burton was an agent and was well known for discovering River and his siblings. She worked with River throughout his career.
Not much is known about this, but what we do know is - It is at the Methodist Hospital in Arcadia, California in a small park area next to the hospital tower, and it's called The River Phoenix Memorial Garden. Also, that there was a private dedication ceremony held after it was put there.
If anyone has any additional information - please email me @ firstname.lastname@example.org