Pottery Mark Identification: Heart with Rays?

Hello!

This was a recent thrift store purchase. It's a small, well-made vase that is glazed on the inside and with some sort of seed depicted on the outside. The bottom has a distinctive mark which appears to be a heart with rays, although it is neither something I recognize nor something I have been able to find online.

So... perhaps someone here reconizes the mark? Any help appreciated, of course.