A couple of years ago my son brought home a potted plant left by behind by a tenant. It had pretty and unusual leaves so I transplanted it into a larger pot and left it outside in a semi-shaded spot
( which apparently was exactly what I should have done). The plant died down in mid summer and I sort of forgot about it until the next spring when in March tiny nubbins of pale green came up and 'exploded' into gorgeous white flowers. The flowers were somewhat short-lived and after they faded the plant sent out lots of large lobed leaves. I have tried a number of times to get an identification but until today I was unsuccessful. At our local nursery this morning an employee took the leaf I brought in and searched the internet until he found it. Sanguinaria Canadensis also known as Bloodroot.
Bloodroot has many medical attributes and googling it reveals how it is used.
This is what the plant looks like in March as the flowers just start to peek out.
This is what mine looks like when in full bloom. If I remember correctly the flowers have a sweet scent.
I'm happy to have my mystery plant identified.