It is unclear how much she was paid for the children, or why she was selling them.
The Department of Protective Services found the children in the process of being sold during a drug raid in Corpus Christi last Friday.
Authorities say a Texas mother with a drug debt to settle is accused of selling her 7-year-old son for $2,500.
Jail records did not list a lawyer for her.
Garza, of Corpus Christi, was charged with the sale or purchase of a child, which is a third-degree felony.
The investigation led them to the discovery of the two additional children, both girls, who were allegedly also going to be sold.
According to an arrest report affidavit of probable cause acquired Thursday by 3News, the seven-year-old boy was sold for $2,500. Additional charges are expected to be filed, officials said. Two other people with the suspect were arrested on drug charges.
After her arrest, officers transported Garza to the Nueces County Jail where she was booked with bond set at $100,000.
DPS is still investigating this case.