Dear Amber,
I believe I found the birth record of Mathias (Matěj) Nacházel, born exactly on 17 February 1837: https://digi.ceskearchivy.cz/4204/55/1027/1046/150/0. He is very likely the person buried at this site: https://www.findagrave.com/memorial/115574616/mathias_nachazel
He had a sister, Františka Nacházel[ová], born on 30 March 1834: https://digi.ceskearchivy.cz/4204/24/1406/1662/97/0.
Their father was Matěj Nacházel, the miller from Služátky (the parish is Chvojnov). Their mother, Kateřina, was the daughter of late Jiří Kratochvíle, farmer from Hněvkovice, and his wife Kateřina, née Sýkora (Sýkorová).
Further siblings can be found in the index: https://digi.ceskearchivy.cz/4204/292/2578/1182/53/0
The water mill is located here, and it even has the same house number as 200 years ago: https://maps.app.goo.gl/WqRXzZu7Uif1FzaR7
and there is a website about water mills which has an entry about it and a few pictures: https://www.vodnimlyny.cz/hu/mlyny/estates/detail/6536-sluzatecky-mlyn
The surname "Nacházel" is rather rare. I only found this combination of siblings in Služátky. I also checked the books from Černov, Skrýšov, Hodějovice, Popelištná and Pelhřimov in general. It's good that some later books in the region have automatically searchable digital indexes so I could only focus on the villages with a high number of records for "Nacházel".
I could not find the marriage of Františka Nacházelová with Josef Dvořák in Chvojnov. It will be way harder to find elsewhere, because the surname "Dvořák" is really common. However, once all of the indexes in Southern and Central Bohemia are automatically searchable in a similar way as on FamilySearch, this could also be solved, just wait a few years...