What is te green grass growing under the Japanese Maple?

The green grass is Japanese Mondo Grass - Ophiopogon japonicus. There is also a miniature variety called Ophiopogon japonicus 'Nanum' which is more compact. Both ideally prefer some shade, particularly in the intense direct sunlight in Australia. Depending on where you live, you could ask your local nursery for advice which is pertinent to your climatic conditions.

Thanks so much for anwering

This is really beautiful. Can you please mention the name of the flowering tree above the japanese maple? Thank you.

The flowering tree is a Japanese Flowering Cherry - Prunus serrulata 'Kanzan'.

Thank you for your time!

Can't wait to see your new garden, this looks terrific!!

The new garden is underway. The main focus of this garden will be food production, although there still is a strong design element combined with experimentation of ornamentals mixed with the vegetables and herbs.....and chickens.