Mushrooms growing randomly in regular substrate with plants

Question

I have planted indoors some red peppers and tomatos in a vertical urban garden, and I saw a mushroom growing in a corner (when I decided to take a picture, it had broken down). Today I have seen another mini-mushroom growing. I am using a regular substrate/soil, this is the one I bought. These are the ingredients (I will translate them so in gardening argot it might be different):

Mix of coconut fiber, blonde peat, black peat, composted vegetal material, organic matter and perlite.

My guess is that inside this "organic matter", with humidity, etc... But I am not sure. I have also seen it twice. What is this mushroom? Is this normal? Are these mushrooms safe(for the plants and/or for me to eat)? It reminds me a bit random shrooms that can grow in your garden (at least it happened to me). I sometimes have my window open (not that often now that it's cold), but I doubt a spore may have come flying, twice. I do not live in the countryside.

Maybe this is a similar question but it did not have any answers.

Answer 1

I can't tell whether the product you used is actually sterilised potting soil, but it seems that it is not. The toadstools/mushrooms are nothing to worry about, they are there because the mycelium from them is present in the soil, and that's there because the soil contains bits of un-composted material such as wood fragments, and this fungal activity is breaking down or digesting those parts. If they trouble you, snap the toadstools off at soil level and get rid of them - they are only the fruiting bodies of the mycelium, but best not to try eating any of them.