Ah, the scent of carrion is in the air! The Arum Vulgaris (also called arum dracunculus, voodoo lily, snake lily, stink lily, dragonwort) is in bloom!
Yes, those are flies promenading on its spadix (the vulgar bit)-- they are lured by the aroma to act as pollinators.
Why would anyone want a thing like this in their garden? I've been asked that more than once and can only say I find this plant strange and wonderful.(I did, however, move it farther from the house after the first year.) There's more about it HERE.