"ste-m" wrote in message

When we moved into our house two years ago, there were small (like a
foot
tall) green plants with spikey leaves in the front garden,

I'd say it's a Yucca. It would grow into a multibranched "tree" in a
warm climate but you could cut off the top and replant that in a pot
or move the whole thing while it's still small. Tough as old boots.