Heading out East of Melbourne about 40 minutes or so, you will arrive at the Dandenong Ranges (not to be confused with Dandenong, also out east, but the latter is a city/suburb with an industrial history). The Dandenong Ranges are a beautiful belt of wooded hills, originally a holiday destination earlier last century for the residents of then Melbourne proper. It is close to my heart, as I lived in the foothills in a one bedroom house perched on the side of a steep slope for many years.
With the proximity of the Dandenongs to Melbourne, it is easy to visit, and take one of the many trails through the forested areas. It is home to the tallest flowering trees in the world, the mountain ash. You will also be stunned by ancient ferns, the cockatoo and parrot population, and if you are very lucky, stumble upon lyrebirds and marsupials.
There are also magnificent cool climate gardens, with the fertile soils, higher rainfall and lower temperatures, it is a gardeners and nurserymans paradise. You can also stop for a light meal or something more substantial and contemporary at one of the many cafes and restaurants, or shop in the small villages dotted about the hills.
Or you can just enjoy one of the many easy walks, and take the opportunity to appreciate the majesty of nature.
There are many many places you can stop and enjoy the trails. Basically all of them are very easy, not strenuous, and you can find yourself losing the road noise and being surrounded by the sound of bell birds and cicadas very quickly.
On a weekend, it can get very busy though. So I do recommend you get there early, otherwise parking can become an issue.
At Kallista, you can stop at the tea rooms, where you can get a pretty reasonably priced meal, with options including fish and chips, or just coffee and cake.
And you will be blown away by the sheer volume of Rosellas and Cockatoos.