Elle, an artist, finds an old canoe in woods behind her property. her neighbors consider it abandoned. elle cleans it, paints scenes on it depicting native american rituals, and displays it in her art gallery. flo, the canoe's original owner, claims it, but a court grants elle title. this is

This is "accession".

Explanation:

When you find something whose owner is someone else, and then you add some additional work on that object and court grants that object to you, this refers to accession. As in the given scenario old canoe belongs to Flo, but Elle finds the old canoe and paints that and when Flo claims that it belongs to him, the court grants Elle title, this is accession.