Has jaggedy edges--growing in a shady area. Anyone know what it is?

It looks like Lambsquarters (Chenopodium album). Lambsquarters (Chenopodium album)

I think you nailed it, Christine! Thanks so much!
Just read this about it:

"Beneficial use in ecological pest control
Chenopodium album is vulnerable to leaf miners, making it a useful trap crop as a companion plant. Growing near other plants, it attracts leaf miners which might otherwise have attacked the crop to be protected. It is a host plant for the beet leafhopper, an insect which transmits curly top virus to beet crops."

Maybe I should site it in a few trouble spots?
Sounds like it is a pretty robust weed, though...

Glad to get a good ID. It's a great plant with a long taproot that can also be used as a nutrient accumulator. It's also edible. Makes good compost. Probably more good things about this plant ~~ but not for everyone because it can get pretty big and makes lots of seeds. Some call it a weed.

yeah, I'll need to give it some thought. I definitely like the idea of using it as an ecological trap.
the long taproot makes it sound like it may not transplant well?