What is the ruling on collecting materials from garbage and selling them, given the possibility of finding valuable items and disposing of them without verifying their owner, despite the availability of other jobs?

It is permissible to benefit from things people discard out of disinterest, such as plastic containers and cardboard boxes. Whoever finds them has a greater right to them. As for earning a living by scavenging for these items in trash, some jurists deemed it disliked if other means of livelihood are available, considering that earning from ignoble professions is disliked if one can practice something better. However, 'Umar ibn al-Khattab, may Allah be pleased with him, said: "A livelihood that involves some ignobility is better than begging from people."

As for valuable items like gold found in trash, the finder is not permitted to own them. Rather, they are treated as lost property, because they are often discarded by mistake, and their owners will likely search for them.