Samantha Eccles says she was furious when she learned her child could be left with nothing after contacting Pennyhill Primary School.
The prospect of her son going without meals at lunchtime has added to the national row that food portions being handed to children are too meagre.
The 41-year-old mother of four children said she was disgusted when she picked up nine-year-old son Jamie’s food which was meant to last five days.
She said: “I actually said to them that I thought they should have it back off me because there was no way that was £15 of food, which was what they were trying to tell me.
“I said to them there was no way there was a fiver’s worth in there.”
A picture of the parcel show it contained a loaf of white bread, a tin of beans, a tin of meatballs, a packet of soup, a small packet of pasta, a portion of cheese, one apple, one orange, one carrot, three potatoes and three pots of yoghurt.
A second parcel came with an extra tin of beans, carrot and apple.
Mrs Eccles said the food was of poor quality with the bread being only two days short of its sell by date and the potatoes were so soft and bruised she couldn’t cook them.
She added: ”I was shocked. I actually thought they were joking with me but they were really serious.”
When she rang the school asking if she could be given vouchers instead she was told it only issued parcels and Jamie could be taken off their list if she wasn’t satisfied.
Angered by the response she said: “I was told that they could withdraw Jamie from free school meals because I was complaining, so he won’t receive anything.
“I said no. I didn’t want that because if the school changed to vouchers system he’d be left with nothing.”
Since she contacted the school the government has announced parents are to be given £15 in vouchers which can be used in supermarkets.
Pennyhill Primary School declined to comment but a statement issued by Sandwell Council, said: “Following a review and new guidance from government, the school will be switching to a voucher scheme next week because that way parents can buy their preferred food from a shop they choose.
“The school has now contacted all eligible parents regarding the voucher system for next week.”