Does anything become incumbent upon me after repenting from taking a dropped item, such as estimating its value and giving it in charity on behalf of its unknown owners?

If the found items are insignificant and worthless, then there is nothing upon the finder. However, if they are valuable, then whoever picked them up and benefited from them without publicizing them for a year must repent. They must estimate their value and give it as charity on behalf of their unknown owners. If the owner is identified, then it must be returned to him, due to the hadith of Zayd ibn Khalid regarding the publicizing of lost property for a year, and the hadith narrated by Al-Daraqutni that it remains a trust until its owner comes.