I've identified the orchid that I have in my garden, its a Crucifix Orchid. Its also known as a poor man's orchid because its so easy to grow and propagate so is cheaper than other orchids. I've never grown orchids before, I had one specimen in a pot of normal potting mix sitting in water. After some research I've discovered that orchids don't like to sit in water! But that one has flowered at least so its not too unhappy, but its leaves are a bit yellow so I will repot it when it's finished flowering. I went up to Bunnings and got some orchid mix and potted some more plants that I pulled out from a dark corner of the garden. I hope I've done the right thing!
I now know this is a Crucifix Orchid, or poor man's orchid
an orchid growing wild in a dark corner of my backyard