Wales is a great place to look for them because of its extreme topography which lends itself to undisturbed grassland habitats and woodlands, many of which are considered internationally important. The climate is also very suitable as it is wet and mild for much of the year.
Fungi have been around for over 400 million years, so it's not surprising that they have evolved into a plethora of weird and wonderful shapes, colours and sizes.
There are about 18,000 different species of fungi in the UK; three times as many as all the other plants put together. However, despite their age and diversity, they remain poorly understood.
We might associate fungi with autumn, when their fruiting bodies grow above the surface, but they are present all year round.
A sunny summer and moist autumn with few frosts should yield a good year for fungi.
Try one of the walks from Derek's latest walking series on BBC One Wales.
Find out about the wildlife you can find on your doorstep.