My daughter writes happiness poems. Try her website at http://wendyspoems.freeservers.com. She has one called Rainbows.
The Young Women Missionary Society at my church sponsored a Rainbow Tea and we acted out this poem ~ hope you can use it. On the web under address where "www. whatever goes" key in the following http://groups.msn.com/FullMoonParadise/Colourmagick.msnw and the poem should appear.
Not a poem, but fun and within your theme. I bought a bag of poured glass prisms from Edmunds Scientifics and gave them away to people who I knew had undergone bad times - just a surprise gift. Not much money so I gave away rainbows. (Nothing to do with occult, etc.). While in the hospital with my Husband, I gave one to the children's ward. The kids love waiting for the rainbow which happens in different parts of the room as the sun moves if the prism is placed in (or glued on) a sunny window pane.
Susan
Another good source is the reference librarian at your local library. They have a book, only in the reference section, that has all kinds of poems. Say you know the first line of a poem but not the title, you can look it up there. There are other sections in that book as well.
Your taxes pay for your local library with all the resources there; make use of them.
Here are some pages with poems about rainbows. Some of them are for kids but might work for your tea.
http://www.songs4teachers.com/colorpoems.htm
http://www.kinderkorner.com/colors.html
http://www.tintota.com/poems/colors.htm
http://www.myelectricrainbow.com/poems.htm
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