Thank you for everybody's remark!
Old, country with a big history ours.
The groschen the rarer one, with what not Polish, but Lithuanian mounting.
Helena wasn't an empress, she was Constantine I.'s mother.
Helena
? - d.329
Mother of Constantine I. Helena was deeply involved with the early Christian church and canonized after her death.
Coins in her name were minted between 324 and 326 and then posthumously circa 340.
Over a dozen mints struck coins honoring Constantine’s mom over the length of several years. This ensured a healthy representation of coins in her name surviving to this day. However, the mints concentrated all their artistic efforts in relatively few reverse types.
As with other Roman empresses of the period, bronzes will be plentiful and affordable even in relatively high grades while the silver and gold pieces will be prohibitively rare and expensive.