...that seem to grow in the garden. I'm unsure if this was a part of some seed packet I sprinkled in the border, or a weed; I suspect the latter because it is so invasive. I've let it be this year but think I may need to clear it out. Anyone know what it might be ?
Always be careful with purple plants. Many of them can be dangerous if consumed and sometimes even touched. However, looks like a purple toad flax https://www.rhs.org.uk/Plants/55263/Linaria-purpurea-Canon-Went/Details
I have heard this called "Purple Loosestrife". I think it is rather pretty, and if I found it in my garden I would be quite pleased, and would leave it alone.