Here are threads from the past three years (I set the filter to "children's" and selected from the results); undoubtedly there are more links in these, and not all the suggestions will fit your criteria (people's opinions on "suitability" vary, of course) --

Songs to sing with Children
Help: Songs for children's program
Children's songs about gardens/plants
Sea songs for children
Lyr Req: animal songs for children
Lyr Req: Songs for young children
Children's singing games
Children's St. Pat's Day songs
Looking For Celtic Songs For Children
English traditional songs for children

~ Becky in Tucson