From The Collaborative International Dictionary of English v.0.48:
Pains \Pains\ (p[=a]nz), n.
Labor; toilsome effort; care or trouble taken; -- plural in
form, but used with a singular or plural verb, commonly the
former.
[1913 Webster]
And all my pains is sorted to no proof. --Shak.
[1913 Webster]
The pains they had taken was very great. --Clarendon.
[1913 Webster]
The labored earth your pains have sowed and tilled.
--Dryden.
[1913 Webster]