Strange texture for seeds

I encountered this bug when looking for lava.

*I climbed a hill at night and spotted the glow from lava.
*I approached the lava.
*I noticed that there was a strange purple/black item on the ground with some wheat seeds near by.
*The items were pick-up-able, and entered my inventory on approach.
*All the wheat seeds in my inventory took this texture.

The texture appears to be a "missing texture" texture.