Yes and no. No, because Canada was formed in 1867 and since that time there has been no significant aggression. Yes, in that prior to Canada existing as an independent nation, the US had many plots to annex the area. As early as 1775 during the American Revolution, what was to become the United States invaded and tried to take Quebec. Then most famously in 1812 Thomas Jefferson tried to annex Canada. Those were the hot wars, but America had designs on annexing Canada through to 1939 with it's "War Plan Red" invasion plan. This was more towards destroying the UK, but would have effective annexed Canada if it had launched. Further, in 1844 presidential candidate James K. Polk's primary campaign issue was to expand the United States to include Texas and the Pacific Northwest. Polk's battle cry was "Fifty-four forty or fight," which meant the United States would accept nothing less from the British than all of the Oregon Country, as far north as the border of Alaska. Polk won but didn't follow through on his campaign promise. As a side-note, I grew up in Canada listening to a famous (sort-of-famous) Canadian band named 54-40.

In terms of non-violent discussions about a potential merger, in the 1890's there was the Continental Union Association which had a minor blip of support in Canada. Otherwise, there's the better known North American Union concept which has long time roots and includes Mexico. It gained some public attention after NAFTA was ratified, but seems no one is taking the NAU anymore serious than the CAU.

So no, not really. Not unless the wars before Canada was it's own country count.