(Reuters) - Impossible Foods, which makes a meatless plant-based burger and is backed by...: (Reuters) - Impossible Foods, which makes a meatless plant-based burger and is backed by celebrities like Serena Williams and Katy Perry, said on Monday it has raised $300 million in the latest round of funding ahead of a possible initial public offering. The fundraising underscores the growing appeal in plant-based food that tries to taste like meat with fewer environmental or health risks. Shares of competitor Beyond Meat Inc, which debuted on Nasdaq on May 2, have more than tripled.