This one looks quite a bit like shaggy parasol to me aka Chlorophyllum rhacodes. It's pretty weird that they grew out of a plant pot, usually that is reserved for Leucocoprinus birnbaumii. I suppose if you gathered soil from outside for the plant you may have accidentally gathered some spores that go well with the roots of the plant. Another thing to test is to slightly cut the stem on one and see if it turns red or bruises with a color of some sort.