TinyFPGA is an interesting series of FPGA boards.
The A1 and A2 boards uses MachXO2 chips, while the B1 and B2 boards uses iCE40 LP chips. Both chip families comes from from Lattice Semiconductor.
The A1 and A2 boards needs a JTAG programmer, like the TinyFPGA Programmer while the B-series boards are programmed via usb. Github repositories TinyFPGA-A-Series, TinyFPGA-A-Programmer, TinyFPGA-B-Series.
The iCE40 seriers can be programmed by the open source Yosys, Arachne-pnr and IceStorm, toolchain.
Resources: The Hobbyists Guide to FPGAs, PicoRV32 - A Size-Optimized RISC-V CPU,