The admission came from Michelle Hollingsworth to whom they were addressed at Annie Lennard Primary School in Smethwick where she worked.
The 55-year-old said her mail was opened by the school secretary Deborah Jones who only put relevant letters on the desk of the head who has alleged Jones dealt with the school's spending.
Mr Mark Jackson, prosecuting at Wolverhampton Crown Court, observed: "If you had seen the bank statements you would have known what was being spent."
The defendant claimed to have had an overview of where the money was going from regular reports to the finance committee.
The two women are accused of buying handbags, shoes, designer clothes and furniture with the school's money while covering the scam with bogus purchase orders claiming the goods were educational.
Hollingsworth admitted under cross examination that some had been forged and continued: "Now I accept that somebody has fabricated the description of these items but I have not fabricated it."
She suggested 57-year-old Jones might be to blame and commented: "She made the whole lot mixed up and it is impossible to follow."
Hollingsworth who maintains most of the designer items purchased on these trips were for the pupils - and occasionally staff presents - but some were for her and she claimed to have paid Jones for these.
The head teacher said she left the school secretary to settle the bills run up on the spending sprees and conceded: "With hindsight I wish I hadn't. I wish I had been been a bit more on the case but I wasn't."
She continued: "Mrs Jones was a trusted member of staff. She did a very good job as far as I knew. As far as I was concerned everything in the school was fine."
Hollingsworth, from Hatherton Park, Cannock, insisted she had never authorised anything on the school's financial management system because she could not use it and concluded: "I never knew I had to. I don't know how Mrs Jones has done it."
Jones, of Barrs Road, Cradley Heath, admits conspiring with the head teacher to defraud Sandwell Council and the school but denies further conspiracies alleged to have taken place with other people during the five year fraud.
Hollingsworth denies conspiring with Jones and all the other charges brought against her. The case continues.