Tangent (that isn't really a tangent): A lot of people will tell you DAA is the Ionian tuning, and DAD is the mixolydian tuning. True enough, as long as you're talking about songs in the key of D. But you you fool around with modes and open tunings for a while, and if you're not afraid to retune your dulcimer, you have a lot of flexibility. (Or ... think about it ... you have an excuse to go out and buy more dulcimers. I have one for DAD, one for DAA, one for CGG so I can accompany myself singing in C, and so on.) All three songs go way back, but Ralph Lee explains them best. Below are some YouTube clips you can listen to. They'll help you learn the songs by ear.
Twelfth of Never/Riddle Song on Mountain Dulcimer
Dulcimer player Judith Giddings, whose YouTube channel is called dulcimerintheforest, plays a nice non-traditional finger-picking arrrangement. She's probably tuned in DAD, but I don't do enough chording myself to recognize chord patterns. I like it best in DAA, and I like Ralph Lee's "Version B" especially, but she does a nice job playing it chord-melody style.
Mary O'Hara singing "I Gave My Love a Cherry"
A very influential Irish soprano who accompanied herself on the harp during the 1950s, O'Hara learned this song from her first husband, poet Richard Selig (originally of Chicago). After his death in 1957, she entered a Benedictine convent but left the order after 12 yers and resumed her career during the 1970s, 80s and 90s.
THE STORMS ARE ON THE OCEAN
The Storms Are On The Ocean cecilmoody2002
There's nothing slick about amateur musician Cecil Moody's version of the song, but it's worth listening to and learning from. He plays it the old-fashioned way, holding the noter with thumb on top Kentucky-style and singing in unison with a simplified version of the melody. This is what the Appalachian dulcimer sounded like back in Appalachia!
Mother Maybelle Carter ( Family) - The storms are on the ocean
At the Newport Folk Festival - in the 1960s?
Sharon White & Ricky Skaggs : Storms Are On The Ocean [Transatlantic Sessions]
Awesome session work from a BBC-TV special. From Transatlantic Sessions 2. Aly Bain and Michael Doucet on fiddle, Jerry Douglas on dobro. Informed speculation on the other backing musicians in the comments.
(The key signature for A mixolydian, like D, is two sharps ... there's a good chart of how the different keys and modes are related on the Small Circle Tune Learning Session website put up by Irish traditional session players in the Denver/Boulder metro area, at The Rocky Mountain Center for Musical Arts. I find it indispensible.) Here are three versions from YouTube.
Ben Seymour playing "Sheep Shell Corn" on an inlaid Cherry Galax Dulcimer
Ben Seymour, of Tyron, N.C., playing the same version we're learning. He doesn't say, but I think he's tuned to A unison (aaaa) to get an A mixolydian scale starting on the open A string. Says Ben, "Playing the great old tune "Sheep Shell Corn by the Rattling of his Horn" which I learned from the playing of Ralph Lee Smith. (Thanks Ralph!!)" Ben made the Galax-style dulcimer I bring sometimes to Prairieland Dulcimer Strings sessions.
Bruce Hornsby/Ricky Skaggs [Kentucky Thunder] - Sheep Shell Corn (clogging)
Bruce Hornsby, Ricky Skaggs, and Kentucky Thunder live @ the Ferst Center in Atlanta, GA on Mar. 29th, 2008. Writes , who uploaded the video to YouTube, "Apparently it's a common practice (on this particular tour) to call people up on stage to clog when the band plays this song as I've seen it on a couple other videos as well." I'd add: It's common practice everywhere, at least down South.
Joe Hermann & Ralph Gordon - Tennessee Mtn Fox Chase /Sheep Shelled Corn by the Rattlin' of His Horn
A fiddle and cello duo. Joe Herrmann and Ralph Gordon play traditional tunes Tennessee Mtn Fox Chase and Sheep Shelled Corn by the Rattlin' of His Horn in a concert performance which is part of the Fiddle Summit music weekend in Shepherdstown, West Virginia. "Sheep Shell Corn" begins at 1:48.