That's right - that's a third type of mushroom!! I don't know what I'm doing but mushroom growers must be jealous!
I did find a few hold outs and tried a 4:1 milk mixture on them - would beer also work? We'll see if that keeps them at bay.
Water may actually be part of the issue, I keep forgetting we've had a very wet spring (last year was so much worse!), maybe as it dries up over the summer the mushrooms will stop coming up.
I'm with Lily; we freak about mushrooms the same way we freak about bacteria. Despite the fact that 95% are harmless and almost half are edible, there is a tendency to panic, especially where young inquiring palates are concerned. Understandable, but like the Hithchikers Guide To The Galaxy says, [url=https://www.mushroomexpert.com/yard.html]"Don't Panic!"[/url]
These are fruiting bodies from fungal nets running throughout the soil; tips of the iceberg really. Most are beneficial to soil structure and provide food sourcing and the best way to break down carbon heavy detritus (bacteria just can't). Your horse bedding addition IS the likely culprit, but straw mushrooms are almost all edibles, so not so bad...
Here's a [url=https://www.fungi.ca/mushrooms.htm]Canadian mycology[/url]source that might be able to help ID your finds, or tell you who can.
You might try dusting with corn starch. There is a fungus that feed on mushrooms called [url=https://en.wikipedia.org/wiki/Trichoderma]trichoderma[/url] tha LOVES corn and ramps up populations fast when fed with it (I guarantee you have SOME trichoderma in your soil, just not enough yet). You can even [url=https://greenmethods.com/site/products/disease-ctrls/#rm]buy the stuff[/url]... also note the Streptomyces strain; these would help replace the existing fungal net you have naturally with beneficial fungii you don't need to worry about, and actually improve your soil. Copper soap fungicides are also organically excepted for the most part; I use them, but sparingly as I don't want to kill my beneficials...
HG
Last edited by The Helpful Gardener on Fri Jul 10, 2009 11:39 am, edited 1 time in total.
Just did the radio show with my friends Len and Lisa. Len was a pathologist for a mushroom farm and said trichoderma was the bane of his existence growing mushrooms, addding that it isn't a matter of total eradication, as some fungal spores will always be present, it's a matter of dominance; who do we select to be the dominant strain? Corn will help select for trichoderma, one of the most prevalent and cosmopolitan fungii in the world... It's one of the few good uses I have for any corn that's not on the cob, that and the corn gluten as fertilizer and weed supressor...
Just wanted to say thanks for the information. I just put up new planters after moving into a new house and used half organic soil. I've just been scraping all those mushrooms off each morning so hopefully after a winter, next spring planting time, they will stop growing. They are growing out of the wood rough planters also.
I have recently solved this problem. The mushrooms popping up in my vegie garden were tall and white. I simply planted my old tea bags in and around the vegies. The tannin helps deter them. Haven't seen anymore since! Hope this helps someone with the same problem!
The mushrooms are your friends, very beneficial for your soil and plants. Let them beautiful, mysterious fungi grow. Most of them are not toxic, and the ones that are wont hurt you buy touching them, you need to actually feed on them.
Quote: "I've been knocking them down and squishing them up,"
That works!
The mushrooms grow on the dead organic matter in your soil. They are not like regular plants with roots taking nutrients from the soil. They are nothing to worry about.
I don't know what I'm doing but mushroom growers must be jealous! 
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It's one of the few good uses I have for any corn that's not on the cob, that and the corn gluten as fertilizer and weed supressor...