Foraging is free, always. The question of whether or not to forage in city parks is a big one. Technically it is illegal, but many people do it anyway. If you would like to avoid this point entirely, consider volunteering to weed a friend's garden or to help weed at the nearest community garden. Melana Hiatt's Edible Wild Plants has excellent information on this subject, as well as a great seed exchange for members of her email group.
Spring is here, even if it is still just a tease in some parts of the world.
Cover and let cool. Serve with crackers or thinly sliced dark bread. Tastes even better after a day in the refrigerator. Spread on a cookie sheet and place in a 150 degree oven with the door propped open. Stir now and then to prevent sticking.