If there are no markings on it to indicate the silver content, such as "Sterling" and number such as "800" ( 800/1000ths silver) or "925" (92.5% silver) or a series of stamps, it's silverplated. Individual pieces of silverplated flatware are of modest value,often sold as part of boxlots of odds and ends.
Re: Derby silver company twisted spoon
If there are no markings on it to indicate the silver content, such as "Sterling" and number such as "800" ( 800/1000ths silver) or "925" (92.5% silver) or a series of stamps, it's silverplated. Individual pieces of silverplated flatware are of modest value,often sold as part of boxlots of odds and ends.