Monarch & Great Spangled Fritillary
Most would likely recognize the butterfly to the far right as a Monarch, but the Great Spangled Fritillary? I had never heard of that. Luckily, along with nearly everything else, there is a site devoted to helping non-experts identify butterflies.
Also, this milkweed appears to be the Common Milkweed (Asclepias syriaca). The USDA page describing the Common Milkweed calls it a mega food mart for insects. However, milkweeds contain cardiac glycoside compounds, which are toxic to many insects and animals. For those insects that can tolerate milkweed, this toxicity becomes a defense against being eaten.
Oval-leaf Milkweed (Asclepias ovalifolia)
This is another milkweed; straightforward, right? Little did I know that there are at least 14 different types of milkweed in Minnesota (14 are listed on the Minnesota wildflowers site). Looking over the choices, the plant pictured here definitely matches the oval leaf species.
The Oval Leaf Milkweed is relatively rare, but most common in Minnesota, Iowa, and the Dakotas.