Dozens of envelopes are also seen spread across the counter at a precinct.
They used to hashtags ‘one Austin safer together’ and ‘thankful’.
However some people pointed out similarities between the handwriting style on many of the notes.
‘Damn. Everyone in Austin has the same handwriting. Public schools must be amazing out there,’ one man tweeted.
A woman added: ‘And why no postage? How did they even get them…?’