The iCEBreaker FPGA board is an open-source educational FPGA development board.
The iCEBreaker is great for classes and workshops teaching the use of the open source FPGA design flow through Yosys, nextpnr, icestorm, iverilog, symbiflow and others. This means the board is low cost and has a nice set of features to allow for the design of interesting classes and workshop exercises. At the same time it allows the user to use the proprietary vendor tools if they choose to.
After the workshop the boards can be be easily used as a development board as most GPIO are exposed, broken out and configurable through jumpers on the back of the board. There is only a minimal amount of buttons and LED that can't be disconnected and used for your own purposes.