Please note the link Snuffy gave above, Wisconsin Folksong Collection, 1937-1946 - there's some really significant stuff there. Some years ago, Rounder issued a CD of a Library of Congress recording of Wisconsin songs. It was issued as an LP in 1960, as as a CD in 2001. The recordings were collected in the 1940s by Helene Stratman-Thomas and others. Here's the track listing:

Folk Music From Wisconsin Library of Congress, Archive of Folk Culture

1. Pompey Is Dead and Laid in His Grave	Dora Richards	2:19
2. How Happy is the Sportsman	J.L. Peters	1:13
3. Lord Lovel	Winifred Bundy	2:43
4. Awake, Arise, You Drowsy Sleeper	Lester A. Coffee	2:41
5. I'll Sell My Hat, I'll Sell My Coat	Mrs. Pearl Jacobs Borusky	0:47
6. Once I Courted a Charming Beauty Bright (Lover's Lament)	Mrs. Pearl Jacobs Borusky	1:50
7. Brennan on the Moor	William Jacob Morgan	4:26
8. The Pinery Boy	Mrs. Otto Rindlisbacher	1:44
9. The Swamper's Revenge on the Windfall	Mr. & Mrs. Otto Rindlisbacher	0:33
10. The Couderay Jig	Mr. & Mrs. Otto Rindlisbacher	0:34
11. Lumberjack Dance Tune	Otto Rindlisbacher	0:33
12. Pig Schottishe	Otto Rindlisbacher	1:07
13. Shantyman's Life	Emery DeNoyer	4:09
14. The Bold McIntyres	Arthur Moseley	1:09
15. The Little Brown Bulls	Charles Bowlen	3:45
16. Young Johnny (Springfield Mountain)	Winifred Bundy	1:55
17. Billy Vanero	Luther Royce	1:39
18. Cranberry Song	Mrs. Frances Perry	1:09
19. On the Lakes of Ponchartrain	Mrs. Frances Perry	1:21
20. The Milwaukee Fire	Robert Walker	2:32
21. Reuben Wright and Phoebe Brown	Hamilton Lobdell	2:47