NHS staff were given bunches of flowers as they visited supermarkets during a dedicated hour for health workers.
Marcelle Tauber-Gilmore, a nurse at a London hospital, said she "welled up a little bit" when she was presented with a bouquet at a Tesco in Pembury, Kent.
Staff had "sat on the floor an hour before opening writing these messages to us," she said.
Dozens of NHS employees across the country have thanked supermarket staff for the gift on social media.
Many said the gesture brought a tear to their eye.
Mrs Tauber-Gilmore, who lives in Tunbridge Wells and works at Imperial College Healthcare NHS Trust in London, said it was the "loveliest, unexpected, joyful thing" at the end of a "very difficult" week preparing for the worst of the coronavirus outbreak.
Supermarkets opened early to people with NHS employee ID after staff complained of being unable to buy supplies at the end of their shift due to panic buying.
"It came at the right moment," Mrs Tauber-Gilmore said. "I was feeling very anxious about going shopping. I was expecting it to be stressful and that it might be frenzied."
She said it was "calm" and well-organised, with a manager checking NHS ID numbers.
Tina Bates, who works for the NHS in Rotherham, thanked staff for the "lovely surprise" after being given a bunch of flowers as she left a Tesco in Stockport.
However, the feedback was not universally positive.
A doctor said one store had been "absolutely rammed" with "everything taken" 15 minutes after the doors opened. They complained of "no toilet roll or soap or antibacterial wipes but [instead] a free bunch of flowers".
Olivia Stadden tweeted to thank staff for the flowers, but said it was "very worrying" the store was so busy "and the workers are so exposed with no protection".
Supermarkets "should be limiting the amount of people they allow in the store at one time," she wrote.