Still don't know about cow's tails, Sharon, but I wanted to comment on a quote found on the second link you posted, earlier in this thread:

May is named for Maia, grandmother, the Goddess of death and fertility. Maia scorns marriage, so it is a good idea to put weddings off until June.

This morning on National Public Radio's Weekend Edition Saturday (found here, later today) there was a piece on the mating behavior of female blackcap chickadees. It seems that if a female hears a higher ranking male beating her mate in a song challenge, she'll go off and have sex with the higher ranking bird, then come back to her partner to help her raise the chickadee chicks. ;-)

Naturally, this reminded me of lines such as: "take the scorn to wear the horn" etc. in May Day carols. Since Maia is a goddess of fertility, she probably doesn't scorn marriage because she doesn't want men and women to get together, but that she demands that women have the right (nay, obligation) to choose their own partners whenever they want to, rather than getting locked into a single marraige vow. During the ages when young women were "given away" in marriages arranged by their fathers, this meant adultery... That doesn't mean that all that "cuckoldry" (or should I say "chickadee-ing"?) actually went on at the time that these songs were first sung, but that idea of sexual license probably lingered in the cultural memory.

And it might also explain why, during Shakespeare's day (based on all the jokes made by his characters), the assumption is that it will be the woman who is unfaithful in marriage, rather than the man...

Just a thought.