The song is Stay In Your Own Backyard (1899). You can find several copies of the sheet music in The Lester Levy Collection. This is a link to the search page, put lilac and trees in the 1st 2 search boxes and you'll get them.

Here's a link to the 1st page (after the cover) of one of them Lester Levy Collection - Stay In Your Own Backyard

Mick