I was wondering if a Democrat, politician, voters, or special interest groups have found common cause with Trump ideas or policy positions as having some positive outcomes?
It depends somewhat on which Democrat. For example, both Heidi Heitkamp and Joe Manchin are moderate Democrats in states that in the last election voted heavily for Donald Trump. Both Senators have similar policies on energy issues because their states produce oil and coal respectively. Trump is considered pro-oil and pro-coal.
Bernie Sanders says that he could work with Trump on infrastructure and trade. Note that Trump's views on trade are closer to the more traditional Democratic views. This is somewhat hidden by the presidential positions on trade, which are somewhat pro.
Other Democrats have suggested that they might work with Trump on infrastructure, carried interest, and trade.
Note that they don't seem to be embracing Trump's method with infrastructure, which relates to encouraging private investment with tax incentives. It's unclear if that might make part of a bipartisan compromise though. Democrats would prefer direct federal spending on infrastructure.
The answer is, Yes.
TL;DR: Political views are a spectrum, so there can be numerous ideas found compelling by representatives of both political parties.
Existing answers provide with some nice specific examples, so let me focus on more general reasons why it is quite possible that a Democrat may find some Trump's ideas reasonable.
Being a Democrat does not necessarily mean, being a
Remember that political views are a spectrum, and you can place yourself anywhere between left and right based on your unique views. One of the biggest tragedies in American politics is the insistence that you must be either "left" or "right," and you can't disagree with your own side. Real humans, however, are not so perfectly ordered. We agree with some policies and disagree with others regardless of what side they fall on. Remember to stay true to yourself, not the prescribed beliefs of each side, to truly understand your political leanings. (source)
The quotation above applies to each aspect of human's life, be it the attitude toward immigrants and international trade, right to carry weapons, balance between social/personal freedom, tax policy, involvement in military conflicts, and virtually anything.
So it is quite normal thing that some (many!) people who consider themselves Democrats may agree with certain policies and initiatives of the Republicans.
Donald Trump's views are not necessarily "classic" Republican.
There's a big controversy within the Rep. party in regard of the recent Trump's initiatives. There can be even some disagreement between Trump and Pence. There are even Republican Presidential electors who refuse to vote for Trump on Dec. 19, 2016 — specifically because they, arguably being "classic" Republicans, have different opinion that Trump has.
People tend to change their opinion. Anyone may disagree with something today but become convinced about it later.
So, we can safely assume that certain initiatives of Donald Trump may be seen rather like "Democratic" than "Republican". An average Democrat, consequently, may find these initiatives attractive and reasonable.
Of course they can.
many of them voted for Trump!
Trump holds many Democrat-popular views.
Not all "Democrats" are the same
1. many of them voted for Trump!
Part of the problem is that your question is very imprecise, in that, in America, there's no single definition of a "Democrat".
Does that mean someone who belongs to Democratic Party as organization?
That's a bad definition; as it's a vast minority of population. Unlike Communist Party in Soviet Union, very few people who vote for politicians of specific party are actually members of the Party as an organization.
Does that mean someone who is registered as a Democrat when registering to vote?
Many Republican-minded voters register "D" if they live in a state with closed primaries and extremely heave "D" leanings, meaning the winner of general election is ALWAYS a Democrat, meaning their only chance to meaningfully vote is in Democratic primaries. Also, as noted in #2 below, Trump himself was a registered Democrat.
Does that mean someone who voted for Democrats?
Well, THAT one's problematic too - while many people vote straight party lines 100% of time, many others split the ticket (vote for candidates of different parties in different races, e.g. D president and R congresscritter). And, moreover, yet many others vote for different parties in different elections!!!
More specifically, if you consider anyone who voted for Barak Obama in 2008 a "Democrat", then a whole bunch of them voted for Trump in 2016 - which presumably means they can find at least a good point in some of his projects.
2. Trump holds many Democrat-popular views.
This isn't surprising, since Trump:
Including the "Economy does better under Democrats" :)
Was a registered Democrat till 2009
Between 1989 and 2010, The Donald gave $314,300 to Democratic groups and candidates and $290,600 to Republicans, according to a Daily Caller analysis of records maintained by the Center for Responsive Politics.
But Trump’s donation gap was even larger during the mid-2000s, which saw the end of Republican congressional majorities and the ascendance of the Democratic party.
Overall in the 2006 election cycle, Trump and his son, Donald Trump Jr., donated $77,200 to Democrats versus only $24,250 on Republicans. Looking back to the 2004 cycle, the pair donated $40,500 to Democrats and only $17,250 to the GOP.
While the Trumps spent nearly $50,000 to elect congressional Democrats, they donated only $1,000 to the National Republican Congressional Committee (NRSC).
Has held Democrat-like views. As per Commentary magazine:
Mr. Trump has supported massive tax increases on the wealthy, a Canadian-style single-payer health care system and is a fierce protectionist. He once declared himself “strongly pro-choice” and favored drug legalization. Earlier this year he accused Republicans who want to reform entitlement programs – the essential task for those who favor limited government — of “attacking” Social Security, Medicare, and Medicaid. Barack Obama couldn’t have stated it better.
3. Not all "Democrats" are the same
While it may seem that way by reading the press or listening to extreme partisans, not all Democrats are the same or hold the same views on every topic. Some hold some views which are more shared with Republicans - ignoring the prior point that much of what is Trump's is closer to D than to R in the first place.
There are Democrats who are pro-gun-rights to bigger or smaller degree.
There are Democrats who are pro-coal (someone else mentioned Governor Manchin)
There are Democrats who support strong immigration controls, for that matter
There are Democrats who dislike globalization