Does anyone know about mushrooms?

I am living in Northern California and have a few small deciduous oaks in my collection. This fall a couple of the pots produced mushrooms. They seemed to be the same kind in different pots. I know these are commonly found on oak roots in the forests. So I don’t think there is anything to be concerned about with them coming up in my pots.
Does anyone know what kind of mushroom this might be?
Is this common to any other of you out there?

Good question Michael - I’ve seen similar mushrooms in my oaks. My understanding is that it’s nothing to worry about as the cap is a sign that something is decomposing in the soil, but I have no idea what kind of mushrooms they are.

looks like Michorizal (spelt wrong sorry) a very helpful fungi to all trees especialy pines

This looks a lot like the common mushrooms that crop up on Vancouver Island. I had been told that it is a sign that wood is decomposing beneath the soil. Last year when i had an outbreak in one area of the lawn I dug down and discovered that our building contractor had buried some wood scraps beneath the surface. This is consistent with what I was advised and the information Jonas provided. Perhaps there is some bark in the potted soil mix?

Looks like a Russula of some type…fairly common in NorCal…

And for safety’s sake…Russulas are NOT considered edible! …at least in California.

Probably a symbiotic micorrhizal fungus. These tend to protect your plant from pathogenic fungus and chemical exposure. I wouldn’t use fungicide on it as it is highly beneficial to the plant. I know certain plants like the japanese black pine will not grow without a certain micorrhizal fungus. Pull your plant out of the pot and look at the root ball. You will probably see what looks like a bunch of spider webs, this is the micorrhizal fungus. If you see this congratualtions, this will highly benefit your bonsai. If not it is most likely not harmful if it is not growing on the actual tree.