Thanks all for the responses. As an update, I've been trying really hard to avoid asking her questions that might inspire dishonesty, with not much success. Example:
Me: "DD, please clear your plate."
DD: "I did." (she didn't, it's sitting on the table)
Me: "DD, please go back and wash your hands (as opposed to asking her if she washed her hands)."
DD: "I already did." (she did not)
It's non. stop. She pretty consistently lies to either avoid having to do a task she doesn't want to do (putting a toy back, hand washing) or to get something she wants (says she hasn't had dinner when she has b/c she wants to have what I'm having, which I was sharing with her anyway). I really don't know what to do. While I have no doubt that preschoolers are "creative," it's hard to believe that most of them lie this consistently, every day, multiple times per day. She's also told me that her friend's father had surgery (he did not) and told her whole class that her father lives in Australia (he does not - here, I realize that she didn't know the name of the town he lives in, and told her, and also talked about it not being ok to make up an answer if you don't know - say you don't know, or you forget)
In terms of role models, I'd say I'm a very honest person, and that we live in an honest household (with my parents). Her father (my X) is a phoney and a fraud. He doesn't spend much time w/them, however, less than 5 hours/week, I'd say.
I'll try to respond to each thought.
Uccomama - I have tried talking to her about honesty and making stories up and cannot get anything out of her, re: reasons. It actually just leads to more convoluted stories. Sigh.
Lilyka - Yes, some of the stuff is cute or creative. Some is not (the handwashing). I'll talk to the teacher about just taking her to check. We've been working on consistent handwashing at home.
Super Glue Mommy - what I'm really bothered about is the lying that I think is to deceive - to get out of doing things, etc. She's 4.25 years old, and has always been pretty socially adept and very verbal, and perhaps I'm wrong, but I do think she understands what happened vs what didn't happen. I don't think she thinks much before she speaks, but I do think she *gets* what's she's doing, to a degree (not the moral nuances, but knows that what she's saying is not actually what happened).
GuildJenn - I've started reading the article, thank you. I'm trying to figure out HOW to teach her the importance of not lying, and what the truth is, etc. Seriously. I've talked to her about it, and talked to her again, and again. It only seems to have exacerbated the lying.
I'm feeling very frustrated. It seems hard to get through an hour without a lie. I feel like I'm hitting my head against a brick wall, and am frankly a crappy mother.