CHICAGO (AP) _ Downtown strollers were offered half-pound bags of popcorn for a nickel apiece in a demonstration to increase city dwellers' understanding of farmers, and show how much influence they have on consumer prices.

''Of course, (some people) were just happy to get a deal on popcorn,'' said Greg Leaf, a spokesman for agricultural manufacturing clients who helped with the popcorn sales Friday.

''And many people were genuinely interested in our message,'' Leaf said Saturday.

Friday's popcorn sale was Chicago's contribution to Agriculture Day, a national observation officially designated for Sunday but was observed at various times across the country.

While the 5-cent unpopped corn was intended to signify the farmer's share of the eventual retail cost of popcorn, 50 cents a pound in Chicago supermarkets, the annual Agriculture Day has a broader message.

''You're entwined with agriculture even if you live in a high-rise in Chicago and never see a field,'' said Leaf. ''And issues that affect the farmer are your issues, too.''

Not only through food are we all linked to the farmer, he said, ''but through fibers for clothing. And a lot of people have jobs related to agriculture.

''So if you're a truck driver and you haul food, you're affected by agriculture whether you know it or not.''

Leaf said the couple dozen popcorn vendors sold out their 3,000 bags of unpopped corn to an estimated 2,000 people.

Nearly everyone acknowledges a need for the products of agriculture ''if he stops and thinks,'' said Leaf.

''So this is a reminder, one time a year, to stop and think.''

Agriculture Day is sponsored nationally by the Agriculture Council of America, and locally by various farm-related organizations.