Last mushrooms and fairy circels

[Seaman]

I have broken William out of the tower and broken all the runes. I am missing the last 19 mushrooms now that i absolutely cant find, I am missing 6 in the lagoon, 1 at the plateu and some here and there. I saw a comment that said you can use the fairy circels to find the last mushrooms- any idea how to use/unlock them? It just says they are not active

[Cormshee]

You probably found out by yourself now, but you need to collect fireflies. As many fireflies as you bring to the fairy circle, as many mushrooms will be shown to you.