Can you grow mushrooms by burying old mushrooms in compost and straw, etc. as in your how to grow mushrooms article? I cannot find anyone who can sell me any mushroom spawn.
In order to grow mushrooms, you need to plant spores (think of seeds) or spawn (think of seedlings). Mushrooms that you buy for eating are picked before their spores develop, and fungi don't sprout from the fruit the way plants do. It's not our policy to recommend products or producers, but if you google "mushroom growing kits," or "mushroom spawn," you'll find hundreds to choose from.
How to grow mushrooms in tray system?
This article may help with growing your mushrooms: https://www.gardeningknowhow.com/edible/vegetables/mushrooms/grow-mushrooms.htm
We had a very old tree cut down and the stump ground down more than 5 years ago. We continue to have very ugly mushroom and toadstools appear in wet and warm weather. Much of the area in a large circle currently looks black. We were told that it would just take time and not to treat the area. We have even considered digging down, putting black plastic or some other weed guard and then filling in with new dirt or grass seed. Any suggestions would be appreciated.
You can treat the area with a fungicide. That will help reduce the mushrooms. Seeding the area with grass will help cover any that is left. There is no reason that grass could not grow there.
Every year these ugly mushrooms grow in my yard. Is there any kind of treatment or something I can pour on them to kill the root and all?
This article should help: https://www.gardeningknowhow.com/lawn-care/lgen/eliminate-mushrooms-in-your-lawn.htm
Found on top of garden soil.
Don't know exactly, but guessing some kind of egg case or nest for some kind of insect. In Florida we have spider egg cases that look a bit like that, about 1/4" in diameter. You could always take them to the nearest Extension Service, they could probably tell you what they are. This site will help you find the closest one:
https://www.gardeningknowhow.com/garden-how-to/info/what-is-extension-service.htm
Can I use crumbled corn stalk to replace wheat straw for preparing mushroom compost? What is the role of corn cob playing in mushroom compost? Thank you!!!
Yes, you can use ground up corn cob or corn stalk (two different things, by the way,) in place of straw. These provide the carbohydrate component of the compost. Here are a couple of articles that will help you clarify your understanding: https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/mushroom-compost.htm
http://extension.oregonstate.edu/gardening/mushroom-compost-use-carefully
I want to start Mushroom Growing business. Would you please help me to select Mushroom type, preparing soil and environment controlled shed. I have 25'x45' space for this project.
Since I don't have any experience in commercial mushroom growing, I wouldn't presume to offer suggestions. I can tell you that in order to start such a business (or any business, for that matter,) you need to do a lot of research and talk to many people already involved in that business. When I googled "getting into the mushroom growing business," I found a long list of sources. I urge you to do the same thing, and spend a few days (or weeks) reading as much as you can, to get an idea of where you're going.
If you're in the USA, you can also use the county extension service where you live; they have information for agriculture as well as home gardeners. This link will help you locate the nearest office:
https://www.gardeningknowhow.com/garden-how-to/info/what-is-extension-service.htm