It's not a big deal; that happens a lot but it's a sign you are leaving the top layer of soil a bit too wet and/or high humidity. They are probably toadstools & could be poisonous so don't eat them lol.
Let the soil dry out a bit and use a mulch on top like pine bark nuggets or straw if you can find it. Shrooms won't hurt your plants just pick it off they won't even care. If you grow in a fabric pot water from the bottom for awhile to help dry the upper layers of soil.
Your mix could have more spores in it but that's not really a bad thing. Toss out any fruits that are growing and scrape off the top layer to remove any spores that were dropped. At least you know your soil is healthy enough to support fungal life. If you do end up transplanting to a larger pot add some granular mycorrhizae directly in the hole and place the root ball right on it. In time it will colonize the container & eventually dominate over any other fungi present.