The Icestudio project gave me a good start. It supports Ardruino style quick start kits / boards. Such as the Icebreaker. Mouser, Digikey etc ship them. Design files for those boards are open source Kicad. Priced like Arduino boards: <<50$ to get going.
I was impressed about how quick and easy it was to get going: one www download for Icestudio on Mac or Windows, then a graphical user interface in which you wire ports, counters, registers, i/o, plus Verilog text blocks if needed, simply by dragging and dropping into a window that i think is a google Chrome instance. From that same window you verify, build and download. Download is over USB via a ftdi2232 into a flash boot rom on your target.
There’s a rapidly growing set of libraries (Collections) that include serial, SPI, I2C, arithmetic, memories, or even a risc CPU.
You can also use the official Lattice starter kits (evaluation boards plus the typical 1+ GB of “free” IDEs, compilers, synthesizers, drivers and what not), but that’s lengthy painful installs as usual, with a strong push to purchase licenses after a couple of weeks…