Three Cornered Garlic

Also known as Three-Cornered Leek.

http://www.wildflowerfinder.org.uk/Flowers/G/Garlic(ThreeCornered)/Garlic(ThreeCornered).htm

Very invasive. The stuff is spreading everywhere here now. It's overtaking the Bluebells...

At least it seems to be edible, so we'll have to start trying to eat it faster than it grows: https://www.wildwalks-southwest.co.uk/all-about-three-cornered-leek/