Can a child solicit donations for a trip?

The answer depends on what you mean by solicit.

Fundraising events that benefit children are usually sponsored by an organization such as a public or private school, parent group, athletic association or official school clubs with adult advisors. Sponsors are subject to laws that govern the handling of funds. The fundraising is done to acquire funds for various types of activities that benefit children and children often sell products to help raise those funds. It is a long-standing custom in the United States and has enabled students to participate in extra-curricular activities for which there is no other source of funding.

If you are approached by a child to make any type of donation you should inquire about the sponsor and make certain you get a clear answer. It should be for a school or church or team you recognize and you can contact that sponsor to verify the event. If you don't recognize the sponsor or get a vague answer don't hesitate to check with the police to see if the soliciting is legal and above board. There are many door-to-door solicitations being carried out by non-local people who simulate official looking fundraising but who simply need cash.