I posted this to What's That Bug, but forgot to get a good image of the proboscis. Here is my original post:

When planting some bulbs a couple of weeks ago, I dug up this pupa. It was in a weedy area with a couple of milkweed plants, among a lot of catnip and other minor weeds. It was also nearby some lilacs. It weighs 5g and I think it is still alive. The only caterpillars I’ve seen in the area have been monarchs.

The reply:
This is the Pupa of one of the Hawkmoths in the family Sphingidae. The Caterpillars are often called Hornworms because of the caudal horn, or Sphinxes because they assume a pose reminiscent of the Egyptian Sphinx. We normally don’t try to identify Pupae found underground to the species level as that is really beyond our means, but since this was a garden, and perhaps there may have been tomato plants growing nearby, this may be the Pupa of a Five Spotted Hawkmoth, Manduca quinquemaculata, which may be seen on the Sphingidae of the Americas website, or the Carolina Sphinx, Manduca sexta, which may be viewed on BugGuide. Both species have caterpillars that feed on the leaves of tomato plants, both pupate underground, and both have sheaths for their long proboscis which causes the pupa to resemble a jug with a handle.

As you can see in these better images, the proboscis does not resemble a jug handle. Additionally, the nearest tomato plant is over 300 ft away. There is also a large tree next to the area, but I am unsure of the species. Other than that, it's just lawn. I also planted wildflowers before, but they were tiny and probably not substantial enough for a caterpillar. I'm not sure if there was a shell around this, as I was just digging without paying attention and might have knocked it out of it.

I plan on keeping it until it pupates. I wonder if I should put it in a container with some soil and put it under it again. I also wonder about temperature, as here in MN the winters get fairly brutal. If I keep it in the house, is it going to try to pupate at the wrong time and be doomed?

There are another couple of images here and here that might give you a little more detail.

Thanks!