Mushrooming and other foraging are time-tested activities that are best learned in a group of people who have been doing it for awhile. By watching an experienced person harvest you can learn more than you will reading this article. There are some issues to consider.
The most frequent concern is over-picking. If you forage close to a metropolitan area this may be a real issue. The greatest concern is soil compaction from lots of people walking the area which changes the organisms that grow there, dries out the soil, and encourages run-off. Looks awful, too. Actual research is scanty, with soil-compaction shown to be the main culprit. I once was called out for walking in a planted field as it would reduce the harvest. The oft-repeated encouragement is that picking the mushroom fruiting body is akin to picking an apple; most of the fungi (90+ percent usually quoted) is the mycelium which grows in the substrate (soil, wood, etc.) and the mushroom is just a small part of the whole. I believe this is true. The studies that have been done have picked all the mushrooms several times a year with no apparent reduction of yield. Whether this would hold for an area that gets constant picking pressure (read, urban area) is only anecdotally known. Casual mushroomers also get upset about commercial pickers and practices like raking for matsutake or truffles which can do real damage to succeeding harvests; currently this is very difficult to impossible to control without regulation and enforcement.
One needs to be aware of where you want to pick. In general, state or county owned lands allow collecting mushrooms but you really need to check; local rules are decided by the superintendent. Some public areas forbid walking off-trail (soil compaction, mostly) making collection difficult. Due to damage to trees, we can no longer collect chaga in MN State Parks. In Minnesota, commercial picking is not allowed on public lands but this is sometimes not enforced. Wisconsin has a “private use only” rule for public lands. We have it better than California and Oregon where you need to apply for permits and strict harvest limits are required and sternly enforced. Respect for private lands is important; at least one European homicide was due to a truffle hunter invading private land. You would probably want to know who is walking across your backyard.
Another issue that comes up repeatedly is whether to cut or pull. For collecting mushrooms for the table, cutting the stem when harvesting may allow the mycelium to reabsorb the energy in the base, although the one study I know did not confirm this. More important to me is cutting limits the amount of dirt I shake over the rest of things in my basket. When collecting fungi for scientific/identification purposes one needs to include the base of the mushroom by inserting a blade under it to keep the whole intact. Perhaps some wish to propagate the mushrooms by replanting the stem butts; Paul Stamets even encourages this, likely more with cultivated mushrooms; however, this is a low-success method.
Another collection issue is to carry your finds in a basket, paper bag, or other air-porous container and to avoid plastic bags which may hasten decomposition. Hey, they’re alive! A less often quoted reason is that by using an open basket, one is helping them spread their spores; I would buy that.
How people treat each other on a foray is important to me. Shepherding a large group through an area leaves learners (ah…all of us) adrift. A large group impacts a wooded area much more than several smaller groups. Small groups encourage sharing between the members; information can be shared with the whole group later at the wrap-up discussion/table. The best learning happens when we feel a personal connection with those we want to listen and ask. An unfortunate disconnect happens between those who chose to leave some of the finds for others and those who pick everything and guard where they got them. When presented with an abundance of mushrooms, I often want to share the joy of finding them with someone in a following group. On the other hand, I had a former head of a mushrooming group tell me to “pick them all, ’cause the next guy will.” This is most pronounced if a person has picked an area each year and at least emotionally considers it “My Patch.” With increasing numbers of foragers, this can be problematic, especially where cultural differences are involved. What’s right? If you are the only picker in a remote area, it seems to make no difference. If you are with a group or a common area, you need to decide how you want to live with others. A final concern is staying in touch with your group; you might decide to take off on your own, but that can cause much consternation for those who have to look for you; carry a whistle and let people know if you are taking off before others.
Most mushroomers value nature and beauty. Picking in a way that leaves the area intact is self-rewarding. And sure a lot more fun.
See you in the woods.