I figured I might as well tackle this while it was on my mind.
Constance Urdang had a decent career for a mid-level poet, but she must have been frustrated at some of the near misses. She scored an early "hit" in Paris Review No. 15 (all the way back in 1956). This may have been one of her first poems in print ("The Madman"), but then she didn't appear in the magazine again until 1999, several years after her death. (I'm quite curious about this, since it must have been submitted by someone else (Donald Finkel?), and there might have been an interesting story in the notes. I'll try to track the issue down.) She also had only a single poem appear in The New Yorker: "Emergency Ward, St. Vincent's," which came out in 1989. This was collected in Alternative Lives, her final collection. Had she not gotten sick, she might have broken through to the next level. On the other hand, she did have a reasonable number (21) published in Poetry over the years, so she wasn't a complete unknown.
I only put about an hour of internet research into it, so this is hardly definitive or an exhaustive list, but these all appear to be uncollected poems:
"The Old Wives' Tale" Ontario Review No. 34 (Spring/Summer 1991)
"The Snowstorm Collector" New Letters Volume 58 No. 1 (Fall, 1991)
"Transcendence" Poetry (May 1992)
"Into the Trees" The Yale Review No. 81 (April 1993)
5 poems. The Chariton Review: Volume 19, No. 2 (Fall 1993)
"Reincarnation, Goodbye: 1992" Ontario Review No. 39 (Fall/Winter 1993-94)
Two poems. Paris Review No. 151 (Summer 1999)
I am particularly intrigued by what appeared in The Chariton Review and the Paris Review in 1999. I'll see how long it takes me to track these down, and if any are particularly memorable, I will consider posting them below. In the meantime, Transcendence can be viewed at the Poetry Foundation website, along with links to her other appearances in Poetry Magazine.
A quick update: I have tracked down everything except the poems in Chariton Review. I thought I had a line on them at UBC, but for some reason they weren't available electronically (when they should have been). I will try one more time* and then perhaps just buy a copy of the magazine. However, due to the truly extortionate shipping to Canada it will have to go to an address in the U.S., which will entail a long delay in getting my hands on them. Bah.
Anyway, for the next update, I will go ahead and list which of the uncollected poems I liked the most. It's late and I can no longer remember the ones that I did read.
* UBC only has 4 back issues (even on-line) when they should have a dozen at least. No idea where that breakdown occurred. So I will just order the stupid thing and see if there is any way to get it into my hands before the spring... Blah.