Looks like Grevillea robusta. Could be Grevillea banksii but that has slightly coarser foliage. Grevillea robusta is the Silky Oak, an Australian tree that is common in your area. It will eventually grow to 35m tall.

Silky Oak was my first thought, too. Even if there's not one immediately in your neighbourhood, sometimes the cockatoos go for the seed pods for food and probably spread by droppings.
Don't even THINK about planting it out unless you own a park or have acreage. A well-grown specimen is a thing of beauty in flower given the space, but in a residential area it will eventually lift your house off its foundations after the roots have destroyed all your underground pipes. Not to mention what the neighbours will do to you if it falls on them :-)

Thanks for your advice, there are plenty of yellow crested cockatoo's visiting the garden so the seed probably came from them. I'll take your advice and I won't plant it but It's a pretty tree I might try growing it in a large planter (on pavers) at least for a while anyway.

Thanks again for your help.