Here is a traditional recipe that you can alter to your preference. As kids, we would pick wild plums and Mom would boil for about 12 minutes and pour into sterilized jars. She even left the pits in and it was the only thing that slowed us down! The preserves were plums suspended in a thick syrup that was amazing on ice cream or served with cream and toast. Cook it a little longer and you will have a jam consistency. You can also substitute the yellow plums for Italian plums. Add a little 4 tablespoons brandy just before placing into jars if you are not planning to serve this to minors!