I used to could play a harp.
source:
LAGS
Entry:
687
Example:
I used to could play a harp.
Modal 1:
used to
Modal 2:
could
Gender:
Male
Race/Ethnicity:
White
Age:
77
Level of Education:
10th grade
Home Community, Town, or State:
MS (Homewood)
Location Collected:
MS (Trenton)
Year:
1974
Relation to Addressee:
subject to fieldworker
Medium:
Spoken
Sentence Structure:
1.0
Status:
Naturalistic