There is the PULP project (http://www.pulp-platform.org/ http://www.pulp-platform.org/) by ETH Zurich and University of Bologna with different open-source RISCV

There is the PULP project (http://www.pulp-platform.org/ http://www.pulp-platform.org/) by ETH Zurich and University of Bologna with different open-source RISCV cores written in (System) Verilog.