Cliff by Rufus, Cliff.nodes (9763) - I was on the website when I noticed there were very little backgrounds so here's one to add and make the Stick Nodes library a little bigger.

Alley by Agent87, Alley.nodes (1754) - A nice alley to use for backgrounds in your animations.

Crowded RHG by K-cept105, Crowded-RHG.nodes (2349) - Good stadium-like background, used for RHG just like Jade vs. GildedGuy.