Wipe rims, adjust lids, and process. Slice or cube. Simmer 10 minutes in water, juice, or syrup. Fill jars with hot pineapple and hot liquid, leaving headspace. Wipe rims, adjust lids, and process.
Prick skins of whole plums with clean needle.
Halve and pit freestone varieties. Simmer plums 2 min-utes in desired syrup. Fill jars with hot plums and liquid, leaving headspace. Wipe rims, adjust lids, and process. Fill jars with raw plums.