Some 2,000 volunteers are collecting money across the country
A TD told to remove a Daffodil Day pin in the Dáil wants the Leinster House dress code to be more fairly enforced.
Mattie McGrath was asked by ushers to take off the flower, supporting the Irish Cancer Society, as political symbols are prohibited under house rules.
Mr McGrath removed the badge but maintains it was apolitical and he should have been allowed keep it.
An Oireachtas committee is considering whether or not the Dáil should adopt a dress code.
The Dáil's Committee on Procedures is said to be considering a report on standards in 40 other parliaments around the world.
Ceann Comhairle Seán Ó Fearghaíl is believed to have requested the report after a 'number of complaints regarding members' attire'.
The issue of an Oireachtas dress code was previously discussed in 2011, but nothing was ever implemented.
Deputy McGrath told the Pat Kenny Show here on Newstalk there are some politicians getting away with far more.
"I was stopped on the landing (and) they just said 'Sorry Deputy, no emblems allowed in here', and I said 'it's only a daffodil' and I had to just respect the order and remove it from my collar.
"I was surprised because every week, during the Tesco strike, we saw dozens dozens of TDs wearing the 'Support Tesco' lapel badges, and Repeal the 8th badges and wearing jumpers for Repeal the 8th and I would never do anything like that.
"I believe the usher was doing their job."
"But I suppose there's uncertainty around what you can wear - my understanding is you can only wear a pin, I wear the Carers Association.
"Another time I was stopped with a little green ribbon on my overcoat for mental health awareness - they're pretty docile statements.
"They're not proposing any cause, they're just trying to help you.
"But there has to be some decorum, and you can't stop someone with a daffodil - it's not a political statement".
It comes as Friday sees more than 2,000 volunteers the length and breadth of Ireland, to mark the 30th Daffodil Day.
They will be selling daffodils, while hundreds more are organising events like coffee mornings and cake sales in their communities.
It all goes to raise vital funds to support people affected by cancer.
Over the course of the day, 150 people will receive a cancer diagnosis in Ireland - and over 40,000 will get the same diagnosis by the end of 2017.
The Irish Cancer Society (ICS) needs to raise over €3m to continue to fund research and to provide information, care and support services to help those facing cancer and their families.
Head of Fundraising with the ICS, Mark Mellett, said: "All across Ireland, in every town and village, there are cancer patients and cancer survivors in need of support, whether they are dealing with a diagnosis, going through treatment, recovering and in remission or dealing with a palliative situation.
"Daffodil Day is the day when everybody in Ireland comes together to show people with cancer and their families that we care, and that we want to stop cancer."
Here are all the events being held for Daffodil Day:
Garden of Hope, Iveagh Gardens: Thousands of daffodils with messages of hope and remembrance will form a garden from 8.00am in the Iveagh Gardens off Harcourt Street.
The public are invited to come to along on Daffodil Day and plant their message, and enjoy the garden.
'Daff Man' dons his daffodil suit: Irish Cancer Society volunteer James Gilleran, better known as Daff Man, will be dressed up in his special daffodil suit on O’Connell Street as he collects funds on Daffodil Day.
James is a longstanding Daffodil Day supporter having been closely affected by cancer in his personal life.
Stormtrooper invasion: Stormtroopers from the 501st Legion will be leaving the dark side behind and selling Daffodils on Grafton Street for Daffodil Day from 10.00am. Watch out for Spiderman too
Flower Power: Independent News and Media are embracing flower power and incorporating the society’s signature Daffodil in the Irish Independent and Independent.ie masthead as part of their support for the 30th Daffodil Day
Light it up: The Convention Centre is lighting up yellow in a show of support for Daffodil Day
Tap and go: Giving goes contactless for Daffodil Day and donors will be able to make contactless payments via their card or mobile wallet (phone)
The devices will be available to use at St Stephen’s Green Shopping Centre and Frascati Shopping Centre, in Blackrock, Dublin - as well as Merchant's Quay Shopping Centre in Cork and Arthur’s Quay Shopping Centre in Limerick
Yellow Vikings: The Viking Splash boat will be decked out in fresh daffodils and balloons outside the Gaiety Theatre from 10.30am to 5.00pm
No pain no gain: Staff at Aviva offices in One Park Place are holding a sponsored male leg wax as part of their Daffodil Day activities
In Newcastle West, the Red Door Art Gallery is hosting their annual coffee morning between 9.00am and 4.00pm with tea/coffee and refreshments and art available.
The Kemmy Business School in the University of Limerick is also hosting a special coffee morning to mark Daffodil Day again this year
A vintage fire truck will be outside Brown Thomas in Cork city, as members of the fire brigade play their part in supporting Daffodil Day
Daffodils on the airwaves with 96FM: The station will be broadcasting live outside Eason's on Patrick Street, Cork from 12.00pm to 4.00pm
A collection is also taking place on Sherkin Island for the first time this year - one of the most southerly islands off the coast
For the fifth year in a row business throughout Drogheda will be adopting the shade of yellow
The McGauran and McDonald families will be hosting their evening tea party in Coffee at Le Cachot in memory of their mothers Josie and Marian. A raffle is being held too
Maxol Mace on Station Road, Castlebar are hosted a coffee morning for Daffodil Day in their Insomnia café.
The generous staff offered free fresh Insomnia coffee for three hours and asked people to come along and make a donation
Clare locals Dan Connolly, Joe Murphy and Alfie Howard will shave their heads bald at the square in Ennis on Daffodil Day
Aldi is also selling bumper bouquets of Irish-grown daffodils across stores throughout the country, with €1 from every purchase going directly to the Irish Cancer Society.