There is a saying: “One person’s trash is another person’s treasure.” Collectors understand this better than most other people. Old ads, milk bottles, worn shoes, spark plugs, barbed wire, insulators, credit cards, swizzle sticks, key-chain tags and empty boxes that once held bullets all are seriously collected by groups who have even formed clubs to trade information. Did you ever think of saving old paper cups? Not just any paper cup. It should be decorated to show it was used at an event like a World’s Fair or the Olympics. Or it should have an important brand name like Coca-Cola or picture celebrities like Hopalong Cassidy. The cup’s decoration must indicate either an event or a date. The Dixie cup, one of the world’s oldest paper cups, was just an idea in 1907. The Public Cup Vendor Co. was incorporated in 1909 to make the cups, and by 1919 it was named the Dixie Cup Co. At first no one wanted disposable cups, but during the flu epidemic of 1918, laws banned public communal drinking glasses. Soon paper cups were also used to hold ice cream and other products, and more companies started manufacturing throwaway containers. In 1930 pictures of animals or presidents were added to Dixie cup ice-cream lids. Movie stars were featured in 1933, war planes and ships in the 1940s, then baseball players in 1952. Top lid prices today are for the 1952 baseball series. Sample prices for cups from past years by various manufacturers include a Coca-Cola cup, 1960, $20; Popeye on a Happy Birthday cup, 1950s, $8; Dairy Queen cup, 1949, $8; and Votes for Women, Empire States, 1915, $200. It pays to save trash.

Q: I am 89 and still have a 1902 bathing suit that belonged to my mother. It’s a navy-blue sailor suit with white trim, leggings and high, laced shoes. The shoes are not in good shape, but the rest of it is. What do you think I could sell it for?

A: Many suits the age of your mother’s came with leggings and shoes. Women took the shoes off, then went into the water, leggings and all. Collectors of vintage clothing might pay $100 or more for your suit.

Q: I am hoping you can help me identify my old green glass bottle. It has a panel shaped like a gothic window on each of the four sides. The embossed words around the bottle are: “Chief Wahoo Electric Tonic, Walbridge Co., Dunsmuir, Cal., Celebrated Remedy, Cathedral Brand.”

A: Your bottle is not very old. It was made in the 1970s by the Wheaton Co. of Millville, N.J. Wheaton made your bottle and others for the gift-shop trade. Some were reproductions of old bottles. Others, like yours, were pure fantasy. There is no such thing as an antique Chief Wahoo Electric Tonic bottle. The shape of your bottle is called “cathedral” because of its gothic window sides. Old cathedral bottles were actually pickle bottles.

Q: Please tell me if a label that reads “Made in Hong Kong” can help date a piece of porcelain?

A: Hong Kong was a British crown colony from 1842 to 1997, when it was returned to mainland China. Hong Kong’s production of inexpensive exports, including porcelain souvenirs and novelties, developed during the 1950s. So most items like those, with a “Made in Hong Kong” label, date from after World War II. Since 1997, items made in Hong Kong for export are labeled either “Made in Hong Kong” or “Made in China.”

Q: I have an antique finger lamp with the name “Ripley & Co.” inscribed on the glass globe that held the oil. The lamp has a rod-type iron handle on one side. The patent date on the lamp is April 5, 1870. Can you tell me more?

A: Ripley & Co. was founded in Pittsburgh in 1866 by six partners. One of the partners, Daniel C. Ripley (the only Ripley involved), patented a process of making a special kind of glass oil lamp. It had a glass font, stem and base with two handles (although it also could be made with just one handle). Ripley’s patents for this lamp were granted in 1868. The April 1870 patent date on your lamp relates to Ripley’s later invention of an iron handle. Ripley & Co. was one of several western Pennsylvania and Ohio glass manufacturers that merged in 1891 to form the U.S. Glass Co. of Pittsburgh. Your lamp probably dates from the 1870s. If in excellent condition, it would sell for about $200.

Q: We have an antique bedroom suite tagged Berkey & Gay. Are you familiar with the company?

A: Berkey & Gay is a company well-known to collectors. Julius Berkey started working in 1859 making doors and blinds. He soon began making furniture and had a succession of partners. George Gay bought half of the company in 1866 and The Berkey & Gay Furniture Co. was incorporated in 1873. It became a leading manufacturer of furniture in the Victorian Gothic Revival and Eastlake styles. Although the company later added the then-latest styles of Mission and Golden Oak, it went bankrupt in 1932. It reopened in 1936, but finally closed for good in 1948.