fpga ethernet 10base-t phy
It can be done. There are many posibilities.
Perhaps, the easiest way is to use an MAC+PHY ethernet chip whit parallel interface, like LAN91C111. More popular and easy to find are chips with PCI interface, but you'll have to implement PCI interface in your FPGA, and uB's PCI port isn't free.
There are cores for MAC. You can use one of them and search for a PHY ethernet chip with MII interface.
I don't know about ready-to-use PHY cores.
Good luck. It's a very interesting proyect. You'll like it.