Ask Mr. Smarty Plants

Indeed, Taxus canadensis (Canada yew) is native to Illinois. Whether it is similar to Taxus baccata remains to be seen.

This USDA Plant Profile Map shows that Taxus baccata (English yew) has been reported as growing in New York State, New Jersey, Pennsylvania and Washington State; however, it is native to Europe, Iran, Africa and Asia. From the Gymnosperm Database, here is an article on Taxus baccata, which states that most members of the genus Taxus are pretty similar, so that helps in establishing similarity to the North Americana native Taxus canadensis (Canada yew). From the Royal Botanic Gardens, Kew Gardens in England, here is another article on Taxus baccata.

So, now that we know what characteristics we are comparing, lets go back to the native Taxus canadensis (Canada yew) to see how similar they are. This USDA Plant Profile Map shows that it grows naturally in the northern counties of Illinois, but not in Madison County on the southwestern border. That doesn't mean it won't grow there, it just means it hasn't been reported as growing there. We always check this to try and find out if the the climate, rainfall and soil would be acceptable. From our webpage on this plant, here are the growing conditions:

"Growing Conditions

Water Use: Medium
Light Requirement: Sun , Part Shade , Shade
Soil Moisture: Dry , Moist
Soil pH: Circumneutral (pH 6.8-7.2)
CaCO3 Tolerance: High
Soil Description: Moist sands or sandy loams.
Conditions Comments: Needs protection from winter sun and wind, heat or drought. Pest free."

From that same webpage:

"'American yew is a low, straggling shrub or ground cover, 3-6 ft. tall and twice as wide, with flat, narrow needles that are dark green above and pale green below. Evergreen foliage takes on a reddish-brown tint in winter. Spreading limbs ascend at the tips. Bright-red, berry-like fruit grows at the tips of the branches."

Both of the articles on the Taxus baccata used metric terms to describe the size of that plant. This member of the Mr. Smarty Plants Team doesn't speak metric but the comparisons in size between the native and your description of size of the non-native sound pretty close. Both are evergreen, both have rather flat needles and both have  bright red berries. Pictures and more information on Taxus canadensis (Canada yew). Pictures and more information on Taxus baccata.

On the Gymnosperm Database referenced above, mention is made that all members of the Taxus genus had a pretty high level of toxicity.

So, if you think your soil and rainfall are sufficiently like those called for in the Growing Conditions for Taxus canadensis (Canada yew), it would seem it would grow in your garden. Whether it would help insulate your basement, we couldn't tell you.