PicnicWit.com provides a comprehensive but not exhaustive collection of examples from various sources, including literature, fine arts, film, music, dance, journalism, food writers, and cookbooks. Both real-life and fictional picnics are listed chronologically, each accompanied by a brief explanation.
Most entries, roughly chronologically arranged, are from European and American sources.
In a 1649 satire, Pique-Nique was the off-beat name for a man and his associates devoted to gluttony. By 1692, piquenique was a trendy indoor Parisian dining custom.
It wasn’t until 1806 that the English term “picnic” became associated with outdoor gatherings, based on a children’s book, The Happy Courtship, Merry Marriage, and Pic-Nic Dinner of Cock Robin and Jenny Wren. To which is added, alas! The Doleful Death of the Bridegroom.

The first outdoor picnic is John Harris’s The Happy Courtship (1806). the illustrator of the 1814 edition is unknown.
Picnics in real life expect a perfect day with clement weather to escape the humdrum of everyday living. Picnics may be enjoyable family outings or elaborate celebrations. Lovers find the outdoors conducive to courtship, and sightseers stop to enjoy a view. On the other hand, scenes of fictive picnics often deliberately challenge expectations. Made possible by artistic freedom, imagined picnics keep the essence of picnicking, sometimes turning topsy-turvy.