Rainforest, a startup that embeds payment processing into other software platforms, has raised $20 million in Series A funding — less than a year after announcing the close of its seed financing. Raising back-to-back rounds was more common in 2021 but we don’t see it happening as often in this new environment. Rainforest’s traction is likely what helped draw new investor Matrix Partners as well as returning backers Accel, Infinity Ventures, BoxGroup, The Fintech Fund, Tech Square Ventures and Ar...