M28

I recently found one of these while relaying a patio in my back garden, I've been living here for 23 years and absolutely no idea how or when it arrived here in Egham, UK. 

It's dated OCT 03 1899, but does not have the M28 on it?

There is an article in TAMS from October 2007 “Those Veeder Tokens” that discusses these. This information comes from https://en.numista.com/L100946

Here is the website to TAMS, the October journal is free to access.

Tokens and Medals Society TAMS