King’s Park is always a good place to see Australian Wildflowers in an accessible place. These pictures were taken in 2014.
Another Metro venue for good Wildflowers is Wireless Hill Park in Melville. These pictures were taken in 2016
A bit closer to Perth is Old Plains Road, running between New Norcia and Toodyay. You have to get out of the car to appreciate these exquisite, often tiny Wildflowers.