Prosecutors in the food stamp fraud trial of State Sen. Tommie Broadwater (D-Prince George's) and four others introduced records today showing that Broadwater's daughter claimed she was out of work because of an auto accident during the same time in 1982 that she told the jury she was employed at her father's supermarket.

The surpise documents, including a "loss of earnings" application to an auto insurance company introduced by U.S. Attorney J. Frederick Motz in federal court here, appeared to catch defense attorneys and Broadwater's daughter, Jacqueline, off guard.

"Are you lying to the insurance company or the jury?" Motz asked her.

"Neither," she answered, with a perplexed look on her face.

The exchange came at the end of the day, with testimony on the subject expected to resume Wednesday.

The development capped a day in which the fashionably dressed, 21-year-old woman described an affluent life style at her parents' Glenarden home, where there was a telephone in every room. She said friends and relatives lavished $1,200 in high school graduation gifts on her, and she once toyed with buying either a Mercedes or Peugeot turbodiesel automobile.

The insurance documents have now become a key factor in the 10-day-long trial. The two Broadwaters and three Washington area men are charged with obtaining $70,000 in purportedly stolen food stamps from an undercover Secret Service agent and laundering the bulk of them through Broadwater's Chapel Oaks Farmers Market in Prince George's County.

Prosecutors contend that $7,300 in cash seized by federal agents from Jacqueline Broadwater's bedroom last March comprise part of the cashed-in food stamps.

But she testified today that she had saved much of the money over recent years from cash salaries paid to her by her parents for work she did at the market and at her father's bail bond business.

Under cross-examination by Motz, she said she worked on a part-time basis at her father's market from its opening in November 1981 until early this year.

Then Motz introduced the "loss of earnings" application with an insurance company in which she claimed she had lost a $225-a-week salary at the market for the eight-month period from March 1982 to November 1982 because of an auto accident in which she was involved. There was no testimony about how or whether she was injured.

The prosecutor appeared to be attempting to cast doubt on her contention that the bulk of the money found in her bedroom was savings from her salary at the market.

After initially showing confusion, Broadwater said she did in fact make as much as $225 a week at the market. Motz then introduced payroll checks showing she was earning lesser amounts--$115 to $167 a week--at the time.

Broadwater is accused of processing stamps allegedly purchased by three other defendants at a fraction of their face value from an undercover Secret Service agent and of redeeming them at their face value from the government.

Jacqueline Broadwater is charged with making fictitious entries in the market's financial records to conceal the allegedly illicit origin of the stamps. All defendants have denied the charges.