Yes, Tulipan is the best known. There's also Tuberosa, Tatarak, Trojad and Trybuła. A few more, but I can't think of any off hand.
Big yellow cassia flowers- Tannera
Tamaryszek(yellow not violet) sprays
He sent Tansy but called it vrotsez, he also had my birth flower nagietek
These are dried flat pressed flowers he has sent because I like yellow
??You could get a list of flowers and find slavized versions of mostly latin botanical names or do you want native. I think Thyme and Lindens (tillia ) grow in Poland natural
traganek ,tojesc,tojad,tatarak ,tulipan,trybula,tobolki,tasznik