Trying to figure out whether this describes a Bradbury story--a couple of young boys who befriend a man who has moved into
their neighborhood. The man is pleasant enough, but does seem to have an almost green tint to his skin. The man is very knowledgable and proceeds to ask the boys to collect and bring him various items, mostly junk, for a project he is working on. The boys agree in the hopes that they will learn what the project is. The man turns out to be a visitor from another planet who is building a spaceship to return him to his home.

Two people from the Google newsgroup rec.arts.books.childrens replied:

Isn't that a Mushroom Planet book, by Eleanor Cameron?
Tink

Sounds like garbled version of the first one, WONDERFUL FLIGHT TO THE MUSHROOM PLANET to me. It's in print and in libraries so the original person can check it easily enough.
Elaine Thompson

I remember something like that years ago in the pulp magazines....Amazing Stories probably...

The Green Man, by Harold Sherman

...and The Return of The Green Man.

But maybe only because the Alien was Green. Hmmm!!

Great! My second guess was the Mushroom Planet series. Thanks much.