The United States has been to the moon. If anyone ever doubts it, they can go there themselves and discover all the trash we left behind.
A website - http://lunarlitter.com/ - has the story:
In all, humans have left an estimated 400,000 pounds of space waste on the moon. While there exists no definitive list of all objects left behind by the manned missions of the 1970s, it’s helpful to consider the tidbits that remained after the very first mission.
A short documentary explains: