Susan, I plant a few snap peas in big pots (at the back of ones I'll later use for tomatoes) as soon as the top inch or two of soil in them has thawed. (The pots with soil are left out all winter.) I will probably do some this weekend. The earliest I've planted in pots was mid-February (very early spring that year). I sometimes have to replant, but generally they do pretty well. My theory is that seed is relatively cheap.

I think there's a thread on the Vegetables forum about planting peas inside in peat pots, and I've read that's a popular way to start sweet peas in the UK. If you have plenty of seed and/or the cost isn't an issue for you, I'd try some outside in big pots.