Emily Slough launched a campaign after finding a photograph on Facebook of her feeding her daughter in Rugeley.
In a show of support, Swansea mother Jade Richards organised a breastfeeding protest in Castle Square on Saturday at midday.
Ms Slough staged her own event in Rugeley.
Ms Slough, 27, said she had "discreetly" stopped to feed her eight-month-old daughter Matilda during a shopping trip on 7 March.
Her campaign has attracted thousands of "likes" on Facebook and more than 1,000 people are expected to attend her mass breastfeeding protest.
Swansea mother Ms Richards, who is originally from Staffordshire, said she was inspired to launch her own event after hearing about Ms Slough's story.
"We had about 120 people join us to support Emily," said Ms Richards.
"Mothers, fathers and families came along. It was a great turn out and great weather.
"We handed out flyers explaining that we were here today in support of Emily and the flyers also contained information about feeding babies and why public feeding is necessary.
"There were details about the Equality Act which says people can't discriminate against women breastfeeding.
"During the event, one lady came up to me and said it was the first time she had breastfed in public without covering her baby's head with a blanket to conceal what she was doing."
Ms Richards said it was hard to explain why Ms Slough had received such a harsh reaction while breastfeeding in public.
"People are not used to seeing mothers breastfeeding in public," she added.
"Mothers are normally discreet when they're feeding, I'm not saying they should be, but when a mother is spotted they sometimes receive odd reactions."
She said people were used to seeing breasts as sexual objects and were "freaked out" when they saw them being used for what they were designed for.
"I think the breastfeeding protest in Swansea will serve as a confidence boost for mothers and it'll give them a chance to meet like-minded people," Ms Richards said.
"Perhaps this could become an annual event and then breastfeeding wouldn't be seen by some as a problem and would help normalise it."
In Staffordshire, up to 1,000 people turned up to the protest organised in Rugeley town centre on Saturday.
Similar events were also taking place in Newcastle, Milton Keynes, Stirling and York.

Mr McKnight, aged in his 50s, was from Hillsborough, County Down.
He was alone in the a two-seater aircraft when it crashed just off the runway at shortly before 11:30 BST.
He was taken to the Ulster Hospital in Dundonald where he was pronounced dead.  An air accident investigation is continuing into the cause of the crash.
The airfield is operated by the Ulster Flying Club.

The 27-year-old woman was attacked at about 20:00 on 20 February while walking along a path between Byres Road and Glenmalloch Place in Elderslie.
Police said three men seen in the area at the time may have seen the suspect or "unwittingly" witnessed something.
The suspect was white, aged between 35 and 50, and with dark receding hair.
He hit the woman, causing her to fall to the ground, and then raped her.
Det Insp Louise Harvie said: "Extensive inquiries are continuing to trace whoever is responsible for this serious sexual assault.
"There are three men that officers wish to trace as they were seen in the area near to where the incident took place, and may have seen the suspect or unwittingly witnesses something vital to this investigation.
"I would urge them to come forward and speak to police."
The first man was seen in Stoddard Square, Elderslie, at about 20:00 on Sunday 19 or Monday 20 February. He is described as between 30-50 years of age and wearing dark trousers and a light top.
The second man was seen near the Wallace Monument in Main Road, Elderslie, at about 20:15 on 20 February.
He is described as being in his 30s, 5ft 10in, of a stocky build with short, dark hair and clean shaven. He was wearing dark trousers and a dark parka-style jacket.
The third man was also seen near the Wallace Monument at about 01:10 on 21 February.  He is described as between 30-40 years old, with a broad build and wearing dark jeans, a black jacket and white trainers.
More than 100 people have supported a breastfeeding protest in Swansea after a Staffordshire mother was labelled a "tramp" for feeding her baby in public.
[NEXT_CONCEPT]
The man who died when his light aircraft crash landed at Newtownards airfield, County Down, on Tuesday has been named locally as Stephen McKnight.
[NEXT_CONCEPT]
Officers investigating the rape of a woman in Renfrewshire have appealed for three men to come forward, saying they could be vital witnesses.