I would ask permission first and maybe donate 50$ to the church for a year of memorial next to them.
Its just a stake and a box of books and a few guarlands. It would be way more easily accessible to people and me than on austin, an ugly road with fast cars. The churchyard by the library box would be ideal.
But the pastor, Sam is his name, may not want the bother of it all.
In which case, austin avenue is also fine, just less peaceful to pray to Laurel.