Richard Wagner had a groove going on, but his music probably wasn’t laid down in groovy wax until long after he left this world to direct a heavenly orchestra.
But this cache really has nothing to do with him. The Wagner of this grove and the nearby cottage (John or Fred, depending on source material) was the owner of this land whose descendants sold it to Harvey West Jr. for the creation of Harvey West Park.
Since the tree cover and steep slopes will challenge your GPSr, here’s a hint for the cache location: Beyond sign about 80 feet, roughly southwest.