When the Walker Art Center decides to get in on the movies and music in the park scene, usually there’s nary a blockbuster on the schedule. Instead, the museum goes deep, screening films that time forgot -- but shouldn’t. This summer, they’ll once again screen avant-garde oddities from other eras on their grassy lawn. The lineup includes Walter Ruttmann’s abstract animated film series Lichtspiel: Opus I-IV (1921–25), and Berlin: Symphony of a Great City (1927). They’ll also share Charles Sheeler and Paul Strand’s Manhatta (1920-21), and The Sinking of the Lusitania (1918), featuring the work of animation pioneer Winsor McCay. Martin Dosh and the Dosh Quintet will play live tunes to certain selections, and food trucks serving up eats will round out the evening.