If you want a few from a common source The Penguin Book of English Folk Songs has 2 entirely in 5/4:

The New York Trader
Ye Mar'ners All

(a few others there mix 5/4 with other rhythms).

Off the top of my head I think there are versions of The Duke Of Marlborough ("I am a general by my birth and Marlborough is my name") and of Bold Reynard The Fox ("Down by the green fields I did ramble in search of bold reynard the fox") in 5/4.

I just did a quick search on my converted abc files of the DT and I think the only one completely in 5/4 is Confess Jehovah (CNFSJHOV).

If you are really keen and I have some time I could look through some of the other standard books.

Mick