See the elaborate, curious, and sometimes sarcastic valentines from the John Johnson Collection, and the blog post this year about Eugène Rimmel (1820–1887).
Of course we know libraries love catalogues, which are useful for so many things. Some recent posts in the ballads.bodleian blog describe the catalogued variants of a broadside ballad sheet containing a song of two constant lovers, the sailor and the farmer’s daughter, who remained true to each other, despite parental objections.
See the Ballads Project at Cecil Sharp House, 23 Feb.