This is a article taken from The West Kerry Newspaper, I can understand it, but is 'riar maith' a set phrase or expression ? and is the expression at the end that refers to the Famine often used ?
It's about 'Ó Bhéal an Bhab cnuas-scéalta Bhab Feiritéar' le Cáit Feiritéar.

Mheabhraigh sí riar maith dá stór scéalta óna muintir roimpi a fáisceadh as bráca an Drochshaoil.

Riar means manage or provide. I don't see riar maith as a set phrase anywhere so I think it just means manage or provide well. Drochshaol is referring to the Famine times

Well riar is one of those words that is often quite awkward, as the number of English words it corresponds to, or can correspond to, is quite large. One of the meanings is shown in Dinneen's dictionary: riar maith móna, "a good supply of turf". So it can mean "a supply or sufficiency of something". I'm not too sure this meaning is frequently encountered, but it is there.

Go raibh maith agaibh.
The reason I asked is that I've found - riar mhaith - given as 'good supply' but riar also means to manage. The second phrase I found quite surprising - is it similar to the image of wringing every last drop of water out of a towel ? - trying to extract what you can from passing a harrow (over a barren field?) in the times of the Famine ? I can't find in the dictionary - ósnadúr - would that be the unnatural? and go beodhúil - lively and keenly ? followed by fluently.

Tá raon leathan ábhar sna naoi scéal deag uaithi: seanscéalta iontais, scéalta cráifeacha, finscéalta ar an an ósnadur, rannscéalta agus scéalta grinn, agus iad uile inste go beodhúil líofa aici.
Tá tuarisc fhéinbheathaisnéiseach (that must be one of the longest words in Irish - I can understand it, but again it's not in the dictionary) léi ann chomh maith.

Well, féinbheathaisnéiseach is a made-up word, to correspond to English autobiographical - there are no words with a prefix féin- in traditional Irish. Féin is rather a qualified - it qualifies a noun - an duine féin for example. Féin on its own doesn't have anything attached to it to qualify.

Is the West Kerry newspaper you're reading produced in Corca Dhuibhne?

It is -
http://www.westkerrylive.ie/features/item/41-ó-bhéal-an-bhab-cnuas-scéalta-bhab-feiritéar.html - written by Lorcan.
I see that autobiographical is more usually written dírbheathaisnéiseach, which is why I couldn't find the word in the dictionary.

"Osnadúrtha" (the 'o' has no fada in the CO) is "supernatural", so "an osnadúr" would be "the supernatural".

I think a good supply fits the best here or well provided

I think what we have here, for me, is:
She remembered a good amount of her stories from her folks before her wrung from the hardship/yoke of the Famine.
.... so I would agree with a 'good supply' or a 'good amount' or a 'good portion'

_________________
Bí cinnte de go nglacfaidh triúr le gach aistriúchán a thabharfar.
Be sure to get three in agreement with a translation given.

"riar" means a portion of, whether in possessions or land and many other things. I had a lot of stories...bhí riar maith agam de scéalta...I had a fair portion of stories......Modern English, Gaelic, Hiberno-English....The languages and dialects have evolved at different rates.....English is evolving more quickly and therefore changing more rapidly than an easier and earlier translation would appear. Because of the dictionaries the meaning is often occluded, not because of the Irish or Modern English, but because of the disparity between the two, now where Hiberno-English has faded.