Mushroom-hunting is a popular activity in many parts of the country. People often search through cattle pastures because cow manure produces the ideal growth environment for some mushroom species. Psilocybe mushrooms are generally only found in old cow piles in states around the Gulf of Mexico. However, it is illegal to pick psilocybe mushrooms in all states except Florida.
Get permission to enter a farmer's field, especially if it has cattle. Trespassing is illegal and can land the offender in a lot of trouble. It is best to ask for permission well in advance of the time you plan to hunt for mushrooms, since you can't be sure when the conditions will be right for mushroom growth.
Enter a pasture 12-36 hours after a heavy rain. Mushrooms require significant amounts of moisture to grow, and the best conditions occur when the humidity has been high for several days in a row. The more moisture available in the air and on the ground, the greater the number of mushrooms likely to be available. Put on a pair of rubber boots before entering the pasture, as the grass may be wet and you will be walking through cow manure.
Walk through the field in a grid-like pattern to ensure you have sufficiently covered the area. In particular, search shaded areas and areas with tall grass. Mushrooms won't be present in fresh cow piles. Instead, they tend to be found in old piles that have dried and sunk into the grass. The best pastures are those with fewer cows, or ones that have not been eaten down.
Collect all mushrooms by snipping their stems with scissors 1/2-inch above the base. This allows the cow pile to keep producing more mushrooms.
Take them home and identify them with a mushroom identification guide. It is a good idea to know what psilocybe mushrooms look like before you start collecting in order to avoid picking them and committing a crime. Only eat mushrooms you have confidently identified in order to avoid consuming poisonous mushrooms.