The flower looks a bit like Saccharum ravennae, and seems to extend well above the foliage, like S. ravennae.

Do you have a photo of the whole plant? Dimensions?

Thanks donn.

Dimensions are about less than 0.5 metres. A couple more photos below.

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Wonder if it's a problem in my area?

It isn't S. ravennae, from which the flower stalks will extend up to 4 meters over 1 meter foliage. The flowers look similar, however, and it looks like there is a white mid-vein stripe on the foliage...another similarity.

Here is my stand of three S. ravennae this year:

The plant you show looks like it has been mowed down during the growing season, witness several stubby green leaves with squared edges.

I don't know what hardiness zone you are in, but many very flowery grasses will reseed in temperate zones.

Wow, dimensions do matter! Looks like it'll be a tough one to ID - will keep looking around. The only mowing this area gets is either by the kangaroos, wild rabbits, wombat or some other animal I think :)