We don't know for sure, but he may have known the river.
Blair originally submitted a list of four possible pseudonyms to his agent, Leonard Moore, telling Moore that he could make pick of the four1:
H. Lewis Allways
There are several reasons Blair chose to use a pen name at all, one being that he thought that "...
Unfortunately he did not, though it's a great thought!
According to this excerpt from a 1997 interview he did on the DragonCon SciFi Channel Chat (yah, before the name change):
What made you decide on Robert Jordan as your pseudonym? Is it Hemingway?
No, it wasn't Hemingway. I simply wanted to separate the different ...
We may never know. Quoting The Atlantic article The Double Life of John le Carré (emphasis mine):
Taking the pen name John le Carré (he doesn’t remember where from),
Cornwell began to write while still working in intelligence.
Panama Oxridge is Paul Adshead.
I don't know whether any clues were hidden in the Thyme books themselves, but the website for the series contains an elaborate puzzle whose solution is the author's real name. As mentioned by @Shokhet in comments, you can see the start of the trail here:
Start by running your cursor over the Thyme clan badge in the bottom ...
From an interview with the man himself in St. Petersburg:
Tahir Velimeev: By the way, how many names does the multifaceted James Oliver Rigney, Jr. have?
Robert Jordan: Not very many, but also not a few. Under the pseudonym Reagan O'Neal the historical novels The Fallon Blood, The Fallon Legacy and The Fallon Pride were published. The events ...
Maybe to increase the likelihood of getting published initially?
To a previously unknown author, a French-sounding name would lend some cachet.
The semi-opaque world of espionage is intriguing, partly because of the perception that insiders have access to sources of information and other resources, not available to the interested outsider.
Going back ...
As far as I know, she always went by Ursula K. Le Guin¹. This is not another case of Iain “Maybe” Banks. (By the way, K is not a middle initial, it's the initial of her maiden name. I don't know why she chose to write under that name.)
At that time and even later many female SF authors hid the fact that they were female by using a pseudonym that either had ...
The source cited (The Paradox of George Orwell by Richard Voorhees) gives a simple reason for the choice of this name:
When he was twenty-seven, he took as a pseudonym the name by which he
is generally known, Orwell, from a river in Suffolk near which he once
lived, and George as a typical English name.
I've scoured the internet for information about this, and it seems that right now, it's not known what Stengl's pen name could be, or even whether or not she's yet published her new series.
The announcement on her blog was less than a year ago (27 January 2017), and she explicitly says that she doesn't want her new pen name associated with her ...