Submitter does not have a specimen
Arum italicum, not on your list of weeds, but on Weedwise in Clackamas SWCD and on various weed websites from Washington state.
Arrow-shaped leaves with white veins about 8" tall on April 9, 2019. It is the second year I've seen it in this location. (And I did NOT plant it.) I fear it may be being spread by birds.