The more you eat different mushrooms of unidentified species, the more likely you are going to die of a poisoning. Are you sure you really know are they different to those you found last time? Or in other words: are you, again, going to find out what their effects are the riskiest way? Or is someone else doing it because of your recommendation? One can't be sure of it the next day either. In some cases the game is already over when you realize that something is terribly wrong, which might well take a week, so please be sensible.
Get a good book on mushrooms and start spotting and collecting them, no matter where. Now, start to pratice identification with them, no matter what kinds of mushrooms they are. That is the only way to learn it properly. Many mushrooms also make a good dinner when you KNOW what they are.
Edit: also, when you talk about cow pastures... where exactly? America or Europe and which parts of it? Where in the pasture, and where exactly? growing in cow shit or somewhere else? No, it isn't as simple as you may think.