Note that this flatly contradicts what every other (Wasatch) forest service employee has ever told me, so if you are planning to do much foraging, you may want to be equipped with information about what you are really allowed to do. On the other hand, if your personal sustainability rules are anything like mine, you will never encounter anyone while foraging, so the point is mute anyway.
If you want information on what you are allowed to do, or a permit to do it, the person to contact is the regional botanist for your national forest. (The botanist I spoke with said the position was changing soon, so I won't give his name here.) Whoever has that position should be well informed about regulations and how to issue permits. I started at the nearest forest service office, and they had me talk to the local botanist, because I was interested in plants, and they took a while to figure out how or who would issue a permit. The picture for this post is my Forest Products Free Use Permit, so you can see what one looks like.
(more after the break...)