They are both listed in the Normal Hill Cemetery in Lewiston
The spelling is different for Ella.

Edla Persis Watson Row 4, Lot 165, Grave 6 Born 1852 Died 1/1/1937 Brower Funeral Home

James Baylis Watson Row 4, Lot 165, Grave 7 Born 1845 Died 4/1/1924 Vassar Funeral Home

Possible other family members in the same row/lot are also:
Cecile Verlin Watson grave 10 B. 1884 D. 11/1967 Vassar Funeral Home
Elisha M Watson grave 2 B. 1852 D. 1930 Brower Funeral Home
Homer C Watson Grave 8 B. 1893 D. 11/2/1918 Vassar Funeral Home
Jay B Watson Grave 9 B. 1890 D. 7/2/1968 Vassar Funeral Home
Lewis Caples WAtson Grave 5 B. 1877 D. 2/1/1966 Vassar Funeral Home
Margaret Jose Watson Grave 4 B. 1883 D. 7/1/1965 Vassar Funeral Home

I hope this helps.