Eimear learned this tradition from her mother (who learned it from Eimear’s grandmother) and has since gotten into the habit of doing it herself.
“I’m Irish, and there’s an old “piseog” [superstition] that if you take a piece of straw from the church manger scene at Christmas and put it in your purse, you won’t have money problems for that year. You’re also not supposed to spend any money on New Year’s Day, because it means you’ll be paying for things the whole year…I’ve asked my mother and she says she’s not sure where the straw tradition came from (although I see plenty of old ladies in Dublin doing it every year, so it’s not just a family superstition), but her mother told her not to spend money on New Year’s Day. My grandmother was born in Belfast and moved to Dublin when she was a child. My grandfather was born in Clare and moved to Dublin as an adult. I get the impression that my grandmother was very close to his family, so it’s as likely she picked it up from them as from her own.”

This superstition is interesting because it reflects the widely held idea that a new year represents a new beginning financially, personally, etc. Americans make resolutions for the New Year, often related to prosperity and during the Chinese New Year, red envelopes containing money are given to children and unmarried/unemployed adults [http://www.history.com/topics/chinese-new-year-traditions-and-symbols].
The tradition of taking the straw from the church manger also reflects the strong presence of Christianity (both Catholic and Protestant, as both often feature nativity scenes of pageants in the church at Christmastime) that still holds in Irish culture. It even permeates a holiday that is not traditionally religious, New Year’s Day, and is incorporated into New Year traditions because it is so ingrained as a part of daily life.