This was so easy and fun to do.

 Brushes that I used are the default Procreate:

• Sketching > 6B Pencil for the sketch
• Inking > Syrup for everything else.
• Painting > Acrylic for texture in some of the details. I'm not sure that I've kept it in the end.
• Vintage > Groovy for the background texture.

I started by blocking the position, number and size:

Next, I sketched roughly over the shapes, and refined the forms:

But now I needed it cleaned up so I can start coloring. I liked this symmetrical version better:

Blocking the colours:

Adding foliage with the Syrup brush - by adding small strokes around the edges, including colour variation:

Fixed the colours and started adding some small details on a new layer, again by drawing and deleting with the Syrup brush:

Added shadows on new layers, and clipped them to the layer below. Also added some more textures here to the stem and bottom of the mushroom cap:

And why not try some other colour variations, each with its own mood and vibe:

The pink pastel one is my favourite. Which one is yours?