Ficaria verna aka Lesser Celandine. Non-native in N America and a terrible spreader. It produces little tubercles which break up and stay in the soil when you attempt to pull the plants. However, it is ephemeral and the leaves will disappear in the Summer. But they'll be back next spring.

Thanks!

see this:

https://www.nps.gov/plants/ALIEn/fact/rafi1.htm

thanks for the info. I'll probably use glyphosate when the temperatures warm up.

Don't wait too long. The foliage wont be there for long. I goes dormant for the summer.

Cool or not, you must act by time is in 50 % bloom.

The neighbor's celandine down the street is already out of bloom. Too late!

The leaves last longer than the flowers. It's not necessarily too late even if the flowers are finishing. But get cracking. Temperature is not important. Don't wait for warmer weather.

OK thanks. some of them are still under the snow but I hope to get out there this weekend and spray them. The PO must have acquired them with the mulch she put down last year, it's loaded with them.