They are just one of those things that happen in areas with high humidity. You can dig them in, pull them out, or ignore them since you are not growing vegetables. They won't last very long. Frequently they are poisonous, so don't be tempted to try them. And welcome to GoY!

Spores of fungi are minute and float in from everywhere. You've done right to remove them, they are just a sign of the compost decomposing which is normal for organic matter. However are there for-get-me-not plants growing or have these mushrooms grown in a seed tray/pot? If the seeds didn't germinate they have probably rotted off. It's too late to grow them again now. Try again in May for 2012. Or you'll have to buy in plants for 2011.

I don't know why but thankfully my forget-me-not flowers are blooming. Volunteer, I noticed that the mushrooms were growing from the wheat husks spread over my plants' soil. Thank you for answering. And thank you too, Wylieintheazores. :D

I looked in a book I use a lot, and it says that they should be sown in darkness, 65-70*F. Have you seen them growing there? Usually it takes a colder winter than in the P.I. for them to flower.